Bombs mark Colombia anniversary

The guerrillas marked Uribe's first year in power with 3 bomb attacks

A truck bomb has exploded in central Colombia wounding about 20 people, in the third attack in as many days.

The blast occurred on Sunday near a petrol station in the town of San Martin, about 200 kilometres (125 miles) south-east of the capital, Bogota.

At least of six people were killed in two previous car bomb attacks.

The series of blasts coincides with the first anniversary of the inauguration of President Alvaro Uribe - who has pledged to crush the country's 39-year-old insurgency.

The BBC's Jeremy McDermott in Bogota says that despite some successes, the president has failed to do serious damage to the 20,000 rebels that lurk in Colombia's jungles and mountains.

Reward

The authorities say the main left-wing rebel group, the Revolutionary Armed forces of Colombia (FARC), is responsible for the latest explosions.

In Sunday's attack the driver had planned to ram the van into the petrol station, but jumped off at the last moment, according to police.

A reward of 20 million pesos ($7,000) has been offered for information leading to the attackers.

On Saturday a civilian was killed and a police officer wounded when a car bomb exploded on a highway about 80 kilometres (50 miles) south of Bogota.

On Friday, five civilians were burned to death by a car bomb in the north-eastern town of Saravena, in Arauca state.

The state is one of Colombia's hottest war zones where rebels and paramilitary forces have been fighting each other over oil resources.