Colombian security forces say they have killed at least 22 Farc rebels in fighting near the Ecuadorean border. Police commandos were dropped by helicopter after Air Force planes bombed a rebel camp in the jungle. The fighting in the Putumayo region happened near the town of San Miguel, where eight policemen died in a rebel ambush earlier this month. President Juan Manuel Santos said it was "the biggest blow in recent times" to the left-wing rebel group. He said the operation was a sign of how he would respond to the war strategy of the rebels of the Revolutionary Armed Forces of Colombia (Farc).Mr Santos said he had given "clear orders" to the security forces to "continue giving these kind of blows without treaty or quarter". President Santos also thanked the government of Ecuador for supporting the operation, saying better co-operation was improving security along the frontier.Farc have stepped up their violent campaign since president Santos took office on 7 August. More than 40 security personnel have been killed so far this month in a series of rebel attacks and ambushes that analysts say may be intended to force the government into peace talks. But Mr Santos has said he will not negotiate with the rebels until they release all their hostages and stop attacks. The Putumayo region is a traditional stronghold of the Farc, as well as a major cocaine-producing area. Both the Farc and the smaller National Liberation Army (ELN) were severely weakened by the tough security policies of President Santos's predecessor, Alvaro Uribe. Colombia's relations with Ecuador were strained under President Uribe after the Colombian armed forces attacked a Farc camp inside Ecuadorean territory, killing the senior Farc commander, Raul Reyes. But the two nations have since set up a joint commission to coordinate security along the border.