Cameroon is scrambling to locate more than a dozen government officials believed to have been kidnapped by separatists fighting for the independence of an oil-rich and long-disputed territory.

Cameroon's government now believes 13 members of its government have been abducted by militants and possibly waylaid to neighboring Nigeria, where kidnappings for ransom are a normal activity in the Nigerian oil delta.

The kidnapped officials, originally thought to number  just 11, vanished sometime between Sunday night and Monday morning.

No rebel group has declared responsibility for the abductions.

Government spokesperson Tchiroma Bakary says the attack is likely the work of the Bakassi Movement for Self-Determination -  a group of militants fighting  for the independence of the country's oil rich Bakassi peninsula.

"The president of the republic is hereby requesting the population living in this part of the national territory to totally collaborate with the forces of law and order and adminsitrative authority," he said.

President Paul Biya cut short a visit to Switzerland, Wednesday, to lead the country's response to the kidnappings.

The situation in the Bakassi penisula is calm, Bakary said, but the president is asking military forces entering the region to exemplify restraint as the country deals with its internal militants.

Bakary says the president is calling for the implementation of all the legal measures leading to the liberation of the hostages as soon as possible.  Bakary says he's also calling for civil and military authorities operating in the region to conform to security measures proscribed by local officials.

Cameroon has only administered the Bakassi province since 2008, 14 years after Cameroon began legal proceedings against Nigeria for the possession of the peninsula. Ownership of the oil-rich area has been in dispute by various European powers and subsequent African governments since the 1880s.