U.N. peacekeepers have stepped up patrols along the border between Ivory Coast and Liberia, notorious for letting through mercenaries and weapons.
The U.N. Operation in Ivory Coast has been patrolling the porous border since Monday.
U.N. force spokesman Colonel Mustapha Dafir says the aim is to ensure the security of the population in the west of Ivory Coast, which has been very volatile in the past.
Colonel Dafir says they will be working in cooperation with the U.N. Mission in Liberia, which will patrolling across the border.
"As we have had more forces allocated, we are able to do more patrols. We are now doing more than 100 patrols around the country daily," Dafir says. "This operation is between us and the United Nations Mission in Liberia."
Newspapers in Ivory Coast have raised concerns that a senior Liberian politician, Joe Wallace, may be bringing Liberian ex-combatants over to Ivory Coast as mercenaries.
Colonel Dafir denies the operation has anything to do with this.
"To my knowledge, we have not seen any particular activities besides what we deal with during the daily operations we perform," Dafir says.
There are more than 8,000 U.N. peacekeepers in Ivory Coast, most of them patrolling a buffer zone, which separates the rebel north from the government south.
Operation "Mayo 2," as the mission is called, will only last for five days, but other operations are planned for the future.