Mediators say Zelaya must return to Honduras Friday

Costa Rican President Oscar Arias, who leads mediation efforts, set a Wednesday deadline for the new talks after two previous rounds failed.

He said the plan was the last he would present as mediator.

The crisis was triggered when Mr Zelaya sought to hold a non-binding public consultation to ask people whether they supported efforts to change the constitution.

Critics interpreted that as an attempt to remove the current one-term limit on serving as president.

The Supreme Court declared his attempt to hold a vote illegal under Honduras' constitution. The military ousted Zelaya from office and sent him into exile on 28 June.

Carlos Lopez, foreign minister in the military-backed interim government, told reporters in the Honduran capital, Tegucigalpa, on Wednesday that there was no chance of Mr Zelaya returning as president.

“This hypothesis of a possible return of Mr Zelaya to occupy the presidency is completely ruled out.”

The previous round of talks broke down at the weekend, though it has been reported that the mediator, Mr Arias, is preparing to announce new proposals to break the deadlock.

Costa Rica's President Oscar Arias, a Nobel laureate, has warned of the dangers of a possible civil war in Honduras if talks fail, and has been urging both sides to continue negotiations. Mr Zelaya has said he may try to return to Honduras as early as Thursday.

A previous attempt to fly back to the country was thwarted after the military blocked the runway at Tegucigalpa airport.

During the day on Wednesday supporters of Mr Zelaya and the interim president, Roberto Micheletti, staged rival demonstrations in Tegucigalpa.