The mayor of Toribio, one of the towns under attack, said the main square was packed with people attending the market when the rebels struck.

Colombian President Juan Manuel Santos said the attacks were an attempt by the rebels to distract the security forces, who are closing in on their leaders.

In Toribio, in Cauca province, rebels drove a small bus laden with explosives into the local police station.

Mayor Carlos Banguero said farmers attending the weekly market dived for cover as the rebels exchanged fire with police.

Two civilians and one policeman are reported to have died.

Toribio has repeatedly been targeted by the Farc, Colombia's largest left-wing rebel group.

The town is located in a mountainous area where the Farc's Sixth Division is active.

Diversionary tactics

Mr Banguero said that to date there had been 13 attacks on the town, in which 41 people had died and hundreds more were injured.

On Saturday, the rebels also targeted Corinto, Caldono, Jambalo and Santander.

In Corinto, a rebel reportedly drove a truck full of explosives onto the main square, throwing himself from the vehicle just before it blew up.

President Santos said the attacks were a cowardly response to the successes of the security forces in the area.

"The rebels are feeling the pressure," he said.

"We know exactly what they're thinking: they're doing their best to distract the security forces because we're taking away their sanctuaries and lairs," he added.

President Santos was referring to a raid by the security forces last week in which, he said, they came close to catching Farc leader Alfonso Cano.

According to Mr Santos, Mr Cano left the camp only 12 hours before soldiers moved in.