"The head of the International Monetary Fund, Christine Lagarde, has warned that a US default could tip the world into recession.
In a US TV interview she said a default would result in "massive disruption the world over".
The US Treasury will start to run short of funds on Thursday if no agreement is reached for it to raise its debt limit.
Democratic and Republican leaders in the Senate held direct talks for the first time in weeks on Saturday.
But there is little sign of any breakthrough, correspondents say.
In an interview with ABC's Meet the Press Christine Lagarde said America must now raise the debt ceiling before Thursday's deadline".
Source: Reuters
