Colombian police have begun arresting leaders of a paramilitary group for failing to cooperate with authorities under a peace deal.

Officials say at least five leaders of the United Self Defense Forces were taken into custody Wednesday.

President Alvaro Uribe has criticized the paramilitary leaders for failing to agree to questioning by officials about alleged atrocities committed during decades of fighting leftist rebels.

He also has threatened to revoke parts of a 2004 peace plan, such as a ban on extraditing paramilitary leaders to the United States on drug charges.

Some paramilitary leaders have said they may abandon the deal because it does not offer enough protections.

More than 30,000 paramilitaries have turned in weapons under the peace plan aimed at ending Colombia's four-decade conflict.

The rightist paramilitary groups were created to help fight leftist rebels, but later became heavily involved in drug trafficking.

Some information for this report was provided by AFP, AP and Reuters.