The cooperation between two countries which have regarded each other as the "great Satan" or part of the the "axis of evil" came as US officials revealed Washington was poised to announce a relaxation of two-decades-old sanctions on Iran's Islamic regime to assist the relief effort after the quake.

The firefighters from Fairfax County, Virginia, joined up with dozens of Iranians in searching the debris of a house where voices were believed to have been heard, nearly six days after a violent earthquake gutted this southeast Iranian town, killing more than 30,000 people.

Danish relief workers, who had found five dead in rubble earlier Wednesday, used special listening equipment in an attempt to locate a couple who had lived in the house after sniffer dogs pointed to a human presence and people suggested voices had been heard.

Surrounded by a crowd of onlookers, the firemen spent several hours digging and listening before a mechanical digger set to work tearing up the base of what was once a brick house.

By late Wednesday, nothing had been found.

While the operation marked the first time US and Iranian relief workers had actively cooperated on the ground, there was some element of confusion as the various teams suggested different methods to deal with the attempted rescue.

"This is even more chaotic than in Turkey, it's nearly as bad as Nairobi," said one US firefighter who had taken part in other rescue operations abroad.

Meanwhile, the 60-strong US medical team set up a field hospital in town, along with their operational camp in the grounds of a Revolutionary Guard cantonment in the town centre.

Jesper Lund, leader of the UN disaster assessment coordination team, said rescuers had brought out only some 50 bodies on Wednesday, compared to nearly 2,000 on Tuesday.

He estimated that 90 percent of the town had been searched.

The United States will suspend currency restrictions and other sanctions on Iran to ease the work of US aid agencies assisting the Islamic republic in relief efforts, US officials said Wednesday.

The temporary suspensions, which will apply only to US non-governmental organizations (NGOs), are to be announced later Wednesday or Thursday by the Treasury and State Departments, the officials told AFP on condition of anonymity.

TERRA.WIRE