SANTIAGO, March 30 (Reuters) - A man died, a police officer was wounded, and 122 people were arrested in Santiago on Saturday night in riots marking the anniversary of the 1985 police slaying of two leftist brothers during the Pinochet dictatorship, police said.

A 28-year-old died after he was shot by protesters who accused him of being a police infiltrator, a police spokesman told Reuters.

A police officer was also serious wounded in the protests, he said. Angry demonstrations to mark the "Day of the Young Combatant," an unofficial commemoration of the anniversary, have become an annual event in the Chilean capital.

Hooded protesters threw Molotov cocktails and shot at police in different neighborhoods around Santiago. The most heated action was in the Villa Francia neighborhood in the western part of the city, which is also where Eduardo and Rafael Vergara were killed more than 20 years ago.

This year's protests began on Friday, when more than 200 people were arrested and police aimed water cannons and tear gas at marchers downtown.

In 2007, 859 people were arrested, some while trying to loot stores, amid shooting and tire burning protests.

The protests are aimed at Chile's capitalist-style economic model and the center-left government, which critics say pursues policies that do not benefit the poor.

Chile is one of Latin America's most stable and wealthy countries, but some parts of its society feel they have been left behind during the country's mining boom. (Reporting by Rodrigo Martinez, writing by Fiona Ortiz, editing by Patricia Zengerle)