The search for survivors trapped in the collapsed State Audit Office building in Bangkok continued on Monday amid reports that life signs were being detected three days after Friday's devastating earthquake.

“Right now, we’re reaching 72 hours of searching and the operation will continue no matter what the hopes are of finding survivors,” Bangkok Governor Chadchart Sittipunt said on Monday.

The Chatuchak District Office had been instructed to take legal action against Chinese men seen sneaking into the area and carrying away documents. It was a disaster area and no one was allowed to enter without permission, Mr Chadchart said.

A Chinese company is the lead partner in the building's construction.

The governor said the investigation into the building's collapse was the responsibility of the city's Department of Public Works and Town and Country Planning. 

Thai and foreign teams were working together at the disaster site. They included a rescue team from Turkey with extensive experience dealing with earthquake damage in their own country and finding missing people alive in the ruins weeks after the event.

Rescuers were using modern technology and sniffer dogs in the search for trapped people, Mr Chadchart said.

Italian-Thai Development Plc, a company in the joint venture construction project, on Monday expressed condolences to the victims' families.