New rules for transparency over financial support to political parties in Northern Ireland will apply to donations from the Republic, senior political sources have indicated.
Northern Ireland Secretary James Brokenshire said details of future gifts are to be published, but declined to make the measure retrospective to the start of 2014.
Unlike the rest of the UK, the identities of donors to local parties have remained secret due to concerns over security, but critics are concerned the veil is harming accountability.
Sinn Fein receives funding from donors abroad, particularly in the US.
At Westminster the DUP's Sir Jeffrey Donaldson asked Mr Brokenshire about donations routed via the Republic of Ireland to political parties operating in Northern Ireland - meaning Sinn Fein.
Mr Brokenshire said the issue "would remain under consideration".
He said he intended to bring forward legislation "that will provide for the publication of all donations and loans received by Northern Ireland parties on or after July 1, 2017".
But sources last night said that the new transparency rules would apply to donations from the Republic.
But there is concern that the rules won't be retrospective, meaning no new information about the DUP Brexit donation worth £435,000 from a group of pro-union business people.
The government had previously agreed to backdate the publication of donations to January 1, 2014.
Alliance leader Naomi Long told Mr Brokenshire: "You bottled this. This was a chance to show you aren't in the DUP's pocket and publish who lines theirs. You failed to grasp it."
Seamus Magee, a retired head of the Electoral Commission in Northern Ireland, which regulates party finances, tweeted: "The deal on party donations and loans must be part of the DUP/Conservative deal. No other explanation."
A spokesman for the government said: "The Secretary of State plans to implement the Conservative manifesto commitment to full transparency for political loans and donations from July 1, 2017.
"We do not believe it is right or fair to impose retrospective regulations or conditions on people who donated in good faith in accordance with the rules as set out in law at the time."
Ann Watt, head of the Electoral Commission in NI, said she expected the first donation and loan report to be published in the autumn. "We would also like to see the necessary legislation put in place, as soon as possible, to allow us to publish details of donations and loans received since January 2014."
Progress is best made in Northern Ireland when all sides of our community can support it. It does not mean that compromise is impossible, but simply that any agreement needs to be fair and proportionate.