Tight security was deployed across Manila ahead of the verdict, with riot police and soldiers keeping hundreds of flag-waving Estrada supporters several blocks from the Sandiganbayan court building.
Police also deployed a special "shield force" around the residence of Gloria Macapagal Arroyo, the Philippine president, who was advised to remain inside amid warnings of a possible repeat of violent protests seen when Estrada was arrested in 2001.
Escorted from court after the verdict Estrada denounced the trial as a sham, saying the special court was "created to convict me", which he said was already expected.
Rose to fame as swashbuckling action film star
Held office of mayor in hometown of San Juan for 16 years
Cultivated image of supporter of poor and downtrodden
Won presidency in 1998 in largest ever landslide
Time in office was dogged by allegations of corruption and illegal business ties
Senate impeachment proceedings collapse in early 2001, triggering mass protests and forcing Estrada from office
Estrada later arrested and charged with plundering state funds
"This is the only forum where I could tell the Filipino people my innocence," he said.
"That's why I took a gamble. I thought the rule of law will prevail over here. This is really a kangaroo court. This is a political decision."
Plunder is a capital offence, though the death penalty was abolished recently.
Passing its verdict the court ordered that $87m frozen in Estrada's accounts be handed over to the government.
The funds, including protection money from illegal gambling operators, embezzled tobacco taxes, and commissions from insider trading, will be "forfeited", the special anti-graft court said.
Special prosecutor Dennis Villa-Ignacio said the case showed that a public official can be charged, prosecuted and convicted regardless of his stature.
"It shows that our judicial system really works," he said.
Minutes after sentencing, Estrada's lawyer said the former president would appeal the conviction.
|Estrada supporters held street protests as |
the verdict was announced [Reuters]
"He is going to fight this out," Rufus Rodriguez said. "He will be acquitted in the Supreme Court."
Estrada, known to his supporters as 'Erap', has maintained his innocence claiming the charges were trumped up by political opponents.
He has accused Arroyo of masterminding his removal from office by conspiring with leaders of the Roman Catholic Church and senior military officers.
Al Jazeera's Manila correspondent, Marga Ortigas, says that during the last six years under house arrest Estrada has become the main opposition figure against the Arroyo administration.
With Arroyo facing allegations of corruption in her own government, our correspondent Wednesday's verdict sends a signal that no-one is above the law - and a similar case could await the current president once her term is over.