Caracas  - At least 90 Colombians were arrested Thursday in the western Venezuelan state of Barinas for travelling without the required documents, Venezuelan authorities said.

The Colombians were travelling in three buses, General Vladimir Padrino, regional National Guard chief, told Venezuelan television.

"We are awaiting the relevant investigation. We do not understand why there was such a mass movement (of Colombians)," Padrino said, adding that he could not rule out that those arrested were paramilitaries.

The arrests were likely to further increase tensions between the two countries.

Four allegedly armed Colombian paramilitaries were arrested earlier this week in the same state.

Last week, Venezuelan police found the bodies of several Colombians in the state of Tachira, on the border with Colombia. The men had been kidnapped during a football game and then shot dead.

At the beginning of the week, two members of Venezuela's National Guard were killed in Tachira.

The left-wing government of Venezuelan President Hugo Chavez has repeatedly clashed with that of right-wing Colombian President Alvaro Uribe.

Caracas blames Colombia for the activities of extreme-right Colombian paramilitaries on Venezuelan soil, while Colombia has repeatedly accused Venezuela of harbouring left-wing Colombian guerrillas.

Chavez has criticized a deal signed last week by Colombia and the United States.

Chavez claimed the agreement - through which Colombia has allowed the US military to use seven bases on its soil to combat terrorism and drug trafficking within Colombia - is an attack on Venezuelan sovereignty. He has vowed to increase border patrols. (dpa)