Health Secretary Jeremy Hunt has sought to cool his bitter row with Andy Burnham over claims his Labour opposite number attempted a cover-up of NHS care shortcomings when he was in government.
Mr Burnham brought in the party's lawyers after Mr Hunt refused to retract an allegation that he was involved in the suppression of a critical report into "failing" hospitals.
Mr Hunt has written to Mr Burnham assuring him that he was not questioning his "personal integrity" or suggesting that he personally covered up evidence of poor care.
The minister added that he believed elected politicians should debate their differences in Parliament or the media rather than the courts.
A spokesman for Mr Burnham said his team would be discussing Mr Hunt's letter with lawyers, although he pointed out that the Health Secretary had still not deleted the original allegation from his Twitter feed.
"The Secretary of State is clearly backtracking. His reply is an apology of sorts, but he seeks to rewrite the tweet rather than delete it. We are considering his response in consultation with our lawyers," the spokesman said.
In his letter, Mr Hunt wrote: "My tweet referred to revelations about political pressure on the CQC (Care Quality Commission) over the publication process for reports of failures in hospital care, and was not a suggestion that you personally covered up evidence of poor care.
"Whatever our differences on health policy, I do not doubt your personal integrity."
Mr Hunt went on however to say that, as health secretary in the last government, Mr Burnham presided over a culture where disclosures of "bad" news about care problems at hospitals was discouraged "for political or other reasons" with "terrible consequences for patients".
He said Labour "must acknowledge and take responsibility for these failures on your watch".
The bitter exchanges were sparked by the release on Friday of emails showing the Department of Health under Labour tried to stop details emerging of a hospital scandal involving higher-than-normal death rates.
Mr Burnham, who was health secretary at the time, was recorded as being "furious" when news leaked of poor standards of care in November 2009, months before the general election.
Mr Hunt seized on the emails as "shocking revelations on Andy Burnham's attempts to cover up failing hospitals".
"We're legislating to make sure this can never happen again," he wrote on Twitter.
Mr Burnham insisted the emails showed only that he was concerned that disclosure rules had been broken and that he "ordered a press release ... be issued later that day".
He challenged Mr Hunt to substantiate his claim or issue a public apology and retraction.
The emails were released by the CQC watchdog following a request by Tory MP Steve Barclay, relating to Basildon and Thurrock University Hospitals NHS Foundation Trust.