A separate exams system for Northern Ireland would be "regrettable", say MPs.
A cross-party group of MPs in the House of Commons have raised concerns about a rush towards separate exams systems in England, Wales and Northern Ireland.
All three nations should continue to run GCSEs and A-levels, says a new report by the Commons education select committee, which urged ministers to "do everything possible to bring this about".
The call, in a report into last summer's GCSE English controversy, comes just weeks after Education Secretary Michael Gove wrote to his counterparts in Wales and Northern Ireland suggesting that differences in exams reform mean that it is time for the countries to go their separate ways.
The MPs also said that ministers and England's exams regulator Ofqual must pay close attention to expert opinion on exams as they overhaul the system, and not ignore warning voices if concerns are raised.
The select committee's new report examined the causes and impact of last year's GCSE English debacle, in which it was claimed that tens of thousands of teenagers received lower results than expected after grade boundaries were moved mid-year.
It lays blame for the controversy on poorly designed qualifications, and says that a "series of avoidable errors" were made under the previous government when the new courses were being developed.
"Several of the problems with GCSE English can be traced to the qualifications development phase," the report says.
"This underlines the vital importance of getting decisions right during qualifications design. Exam board experts raised concerns at the time, but these were not acted upon by the regulator.
"One of the crucial lessons to be learned from this episode is that Ofqual and ministers should listen when concerns are raised during qualification development, especially when they come from specialists in the field."
It adds that the coalition Government is making widespread changes to GCSEs and A-levels on a tight timetable, and that Ofqual must be prepared and willing to step in if it has concerns about the changes.
Under the current system, GCSEs and A-levels are jointly "owned" by England, Wales and Northern Ireland, the report says.
But it adds that these arrangements have been "tested to the limit" in recent months, amid major exams reform.
Mr Gove has announced plans to overhaul GCSEs and A-levels in England. The reforms will see new GCSEs in academic subjects including English and maths introduced in 2015, as well as revamped A-levels in a number of subjects. The proposals represent the most radical overhaul of examinations for 16-year-olds for a generation.
'Natural consequence' of devolution
Wales and Northern Ireland still have some decisions to make on reforming the qualifications, but differences are already emerging over how each nation will do this.
In a letter to Welsh Education Minister Leighton Andrews and Northern Ireland Education Minister John O'Dowd last month, Mr Gove said it was clear from discussions that the reforms were leading to "very different qualifications", adding that this is a "natural and legitimate consequence of devolution".
Mr Gove added: "I believe that the time is right for us to acknowledge that three-country regulation of GCSEs and A-levels is no longer an objective towards which we should be working."
This is opposed by the select committee, which says: "Relations between ministers in England and Wales are clearly under strain, as the era of three-country qualifications and regulation appears to be coming to an end.
"We believe that such an outcome would be regrettable and hope that even at this stage the joint ownership of GCSEs and A-levels will continue. We urge ministers to do everything possible to bring this about."
Select committee chairman Graham Stuart said: "The Education Committee is concerned that there is a rush towards separate exam systems for England, Wales and Northern Ireland, without careful reflection on what might be lost, or consensus that this is the right thing to do."
He adds: ""The turmoil surrounding last summer's GCSE English results highlights the importance of carefully developing new sets of exams.
"A series of avoidable errors were made when the current GCSE English was being designed under the previous Government. Failures in the modular approach, and the moderation of internal assessments, led to a highly unsatisfactory level of confusion.
"When pursuing future reforms, it is crucial that ministers and Ofqual pay careful attention to expert opinion and don't ignore warning voices.
"They must understand how much pressure schools and individual teachers are under to deliver results, and ensure that the exams children take are robust enough to withstand that pressure."
A Department for Education spokesman said: "This report is clear that the problems in last year's English GCSE can be directly attributed to the design of English GCSEs, in particular the modular approach and the high level of controlled assessment. The previous judicial review also came to that conclusion that it was the structure of the qualification that was to blame.
"That's why we took immediate action to get rid of GCSE modules and are taking action to reduce controlled assessment."
An Ofqual spokesman said: "We welcome the select committee's conclusion that the poor design of the GCSE English qualification resulted in the problems last summer. This supports our own conclusion and that of the High Court.
"The committee is urging us, and others involved in the exams system, to learn lessons from what happened. We have already put in place a number of changes to make GCSE English more secure, and indeed the committee's report welcomes these steps.
"We are also making sure that the lessons about qualification design and how they work in practice in schools are influencing our work in reforming GCSE and A-level qualifications.
"We wish to see high-quality qualifications that are worthwhile to study and teach, and which can withstand the pressures of the accountability system."
The select committee's report comes on the day that Ofqual is due to publish a consultation setting out proposals for GCSE reform.
It is likely to include details of plans to axe coursework in the majority of subjects, introduce end of course exams, curtail re-sits and overhaul the grading system. This could mean scrapping current A*-G grades and replacing them with a numbered system.
The DfE is also expected to publish new information on the content of key GCSEs later today.
'Public confidence damaged'
Responding to the select committee's report, Brian Lightman, general secretary of the Association of School and College Leaders (ASCL), said: "Public confidence was damaged by last year's GCSE English results, which makes it even more important that the government gets it right with the current reforms.
"A rushed implementation that ignores the views of teachers and experts will do nothing to build public trust.
"There is widespread agreement that GCSE can be improved, and that reforms must have at their heart the long term, best interests of young people and employers.
"There must be time built in to plan, test and implement new qualifications properly. Pushing reform through too quickly creates a huge strain all the way through the system, especially as there are already major changes to A-level and the curriculum to contend with.
"It was not the modular structure that caused problems with last year's English results, but the way that changes were introduced."