The Sri Lankan government has denied reports that it has agreed to hold peace talks with Tamil Tiger rebels.
Troops and rebels have fought fierce battles in recent months
A defence spokesman in Colombo said the government had not been consulted by international donors, who made the announcement in Brussels on Tuesday.
Donors said both parties had agreed to talks in Oslo "without preconditions" and urged an immediate end to violence.
Observers hailed the news as a potential breakthrough in efforts to halt Sri Lanka's escalating conflict.
The response from Colombo came within hours of the announcement from Brussels.
Defence spokesman Keheliya Rambukwella denied any agreement to such negotiations. He criticised Norwegian mediators for making such a statement without consulting them.
"The government of Sri Lanka is highly disturbed with regard to the statement made by the Norwegian facilitator, as the government neither agreed for unconditional talks nor was consulted," it said in a statement.
The government later made clear it was still "strongly committed" to talks - but only if the rebels agreed to "a comprehensive and verifiable cessation of hostilities".
Senior diplomats say the government had agreed to talks without preconditions and this has been a long-stated stance.
The BBC's Dumeetha Luthra in Colombo says the only difference is that the Tamil Tigers have now also said they are willing to come to the table, essentially calling the government's bluff.
Mediators had said on Tuesday that negotiations would start by early October.
Norwegian Minister for International Development Erik Solheim told the BBC: "Both parties have expressed willingness to come back to the table. We expect the violence will be stopped.
"The government has throughout its existence for 10 months repeatedly told us that they are ready for talks without any preconditions.
"And the LTTE [Liberation Tigers of Tamil Eelam] has today confirmed that they are ready for talks without any preconditions."
Billions of dollars in aid pledges intended for rebuilding Sri Lanka rest on progress in talks aimed at a lasting peace.
Thousands of people have been displaced in northern areas
Months of heavy fighting have displaced more than 200,000 people. Hundreds have been killed in violence this year.
Last week, government forces captured a strategic rebel stronghold in the north-east. They have also pushed into rebel territory in the northern Jaffna peninsula.
Norway brokered a ceasefire between Sri Lanka's government and the Tamil Tigers in 2002 which is still technically in place, despite this year's violence.
The two sides held a number of rounds of peace talks until the rebels pulled out in April 2003 saying they were being sidelined.
The government and rebels did meet earlier this year for talks aimed at shoring up the ceasefire, but made no headway.
More than 60,000 people have been killed since the rebels began their fight the 1970s for a separate homeland for minority Tamils in the north and east.