MANILA -- Thousands of farmers and left-wing activists burned an effigy of President Gloria Macapagal-Arroyo near her office Friday, demanding justice for 13 people killed by troops more than two decades ago.

The march commemorated the 1987 Mendiola massacre, which was named after a bridge that leads to the presidential palace where soldiers gunned down 13 protesters demanding land reform. No one has ever been charged for the killings.

Click here for stories and updates on the Sinulog 2010 Festival.

Hundreds of riot police were on guard Friday but did not try to stop the protesters. Demonstrators also said 560 farmers had been killed since Arroyo took office in 2001 to suppress peasants' demands for land.

"Nothing has changed 23 years after the Mendiola massacre," said Imelda Lacandazo, a spokeswoman for Kasama, a federation of peasant organizations.

Protesters burned a cardboard caricature of Arroyo and chanted slogans for justice.

A third of the Philippines 90 million people are poor, many of them landless farmers, and agrarian unrest helped spark the 40-year-old communist rebellion in the Southeast Asian country.

Commenting on the allegations that hundreds have been killed in recent years, Lieutenant Colonel Romeo Brawner, a military spokesman, said soldiers who acted on their own have been charged, and 15 cases were pending in court.

Brawner said the figure of 560 killed was inflated.

Other than demanding justice for the deaths, the activists also pressed for agrarian reform, including redistribution of huge land holdings held by the country's richest and most politically influential families.

The left-wing alliance called Bayan has urged politicians running in May 10 elections to implement such reform.

A year after the Mendiola massacre, late President Corazon Aquino signed a law that redistributed land to tenant farmers.

The law, however, contained a provision exempting large landholdings - such as her family's sugar hacienda - from redistribution, and instead gave farmers nominal stock ownership in the estates.

"We cannot have social justice in our country as long as landlords still hold large tracts of land, and the farmers continue to be dispossessed of their land," said Representative Liza Masa, who joined the protest. (AP/Sunnex)