The Sri Lankan prime minister appears to have rejected a power-sharing offer made by his rival, the president.
The PM's side says it had not been shown the proposal
Officials close to Ranil Wickramasinghe said the offer - involving division of responsibilities in the defence ministry - was unworkable.
President Chandrika Kumaratunga sparked a constitutional crisis earlier this month by taking over the ministry and declaring a state of emergency.
The two leaders' power struggle centres on peace talks with Tamil Tiger rebels.
President Kumaratunga sacked the defence, information and interior ministers and took over the defence portfolio saying security was being jeopardised.
Supporters of the prime minister said the joint committee established to try to resolve the power struggle was unaware of the president's proposal, which was leaked to state media on Friday.
"We had ...a different formula to which both the president and prime minister had agreed," said committee member Malik Samarawickreme, who is chairman of Mr Wickramasinghe's United National Party.
"We were looking forward to going forward with that - we just had to work out the details. But this is something totally new," he said.
Another anonymous government source quoted by AFP criticised the proposal saying: "You cannot conduct cohabitation negotiations through the state media."
'National peace delegation'
A statement from the president's secretariat said the proposal was designed "to capture and further the creation of a national consensus and collaborative spirit" between the rival factions.
The seven-page document leaked from the president's office spelled out the power-sharing proposal on Friday.
It suggests the president authorises the prime minister to appoint a minister to assist her on defence matters.
President Kumaratunga says she is acting in the country's interests
This assistant minister would handle issues relating directly to the peace process with Tamil rebels, such as the ceasefire, the international monitoring team and the Norwegian facilitators.
But overriding control for all defence matters would remain with the president.
The document also spells out a vision for the future of the peace process - saying that after one or two rounds of talks, the government would submit an overall framework for proposals to be given to the rebels.
Then, it says, a national peace delegation would be formed, presumably to replace the current negotiating team.
The Tamil Tiger rebels have yet to respond to the leaked proposal, but the BBC's Frances Harrison in Colombo says they might well feel the president is trying to start the whole peace process from scratch again after two years.