Arroyo was in the US on an official visit when Aquino passed away.

'(On) behalf of a grateful nation, President Arroyo extends her most sincere condolences to the family of the late president,' her spokesman Cerge Remonde said in a radio message from the US.

'A period of national mourning will be formally declared in honour of the late president Aquino,' he added.

Remonde said Arroyo would discuss with her delegation if she would should cut short her trip and immediately return to the Philippines. She was scheduled to return Wednesday.

Early masses were offered for the repose of Aquino, who led a four-day bloodless 'people power' revolution in 1986 that toppled the dictatorship of the late Ferdinand Marcos.

Filipinos in and outside the Philippines had been offering prayer vigils and masses for Aquino since she was hospitalized.

Yellow ribbons were also tied on street lamps, trees, fences and buildings throughout the Philippines. Yellow was Aquino's symbol in her fight against Marcos.