Arroyo's aides say there is mounting proof that the 296 rebel junior military officers and enlisted men who seized a top-end serviced apartment in the Makati financial disctrict on Sunday were well-funded and had planned to spark a larger uprising to unseat the government.

Raids on two houses which authorities say were used by the soldiers as staging points for the 22-hour rebellion yielded circumstantial evidence pointing to Estrada, who has denied any links and accused the government of setting him up as a fall guy.

"I'm being set up and forcibly being implicated," said Estrada, detained at a suburban military hospital. Estrada is on trial for massive corruption yet remains immensely popular to poorer Filipinos.

One house where munitions and insignia used by the rebels were found is reportedly owned by Laarni Enriquez, one of Estrada's most well-known mistresses. The other house is owned by detained top Estrada aide Ramon Cardenas, who was indicted for rebellion on Tuesday.

An Estrada political ally, opposition Senator Gregorio Honasan, is also being linked to the rebellion.

"Estrada still looms large in the background of Philippine politics," said security risk consultant Rex Robles.

Estrada, 65, was deposed in a military-backed popular upheaval halfway into his presidency in January 2001 and was succeeded by his elected vice president Arroyo.

Bruce Gale, a Singapore-based political risk analyst with Hill and Associates, said "the mutiny by disgruntled soldiers... was originally planned as a genuine coup attempt by pro-Estrada groups."

He cited government sources close to the investigation as saying that "the original plot was hatched in early June and was originally intended as a coup attempt to topple the incumbent administration."

The occupation of the upper class Ayala Center was not part of the original plan but was resorted to after the plot was discovered.

"The mutiny appears to have been staged to destroy Arroyo's chances for re-election," Gale said, pointing out it was mounted on the eve of the president's annual state of the nation speech to Congress on Monday.

The quick surrender of the mutineers "limited the political damage to some extent" but it was still unclear whether it will destroy Arroyo's bid to run in the 2004 presidential electionsm, Gale said.

Arroyo has not been naming names but said the rebellion "can only be the handiwork of the most desperate groups that have completely lost their moral compass."

Her spokesman Ignacio Bunye said "what is becoming clear is that there are civilian elements and their participation took place before, during and probably a little after the July 27 incident."

Asked if Estrada was involved, Bunye said: "We are looking at all angles at this time. We don't want to point fingers at any particular groups but right now the physical evidence tends to show that the mutineers would have launched (their coup) without any outside help."

Renato de Castro, a political scientist at De LaSalle University, said however he did not think Estrada was involved.

"He is there in jail and basically he has no more interest in the coming elections. He's probably traumatised by the experience (of his ouster)."

WAR.WIRE