Cameroon sources said late on Monday that almost 500 Nigerian soldiers fled over the border away from Boko Haram Islamists.

"I can't give the exact figure, but they should be 483 or 484 soldiers," said Cameroon defense spokesman Didier Badjeck. It's understood the soldiers had been fighting the insurgents in the border town of Gamboru Ngala, in north-eastern Nigeria, which is now said to be under Boko Haram control. Some residents of the town are understood to have also fled.

Badjeck said the soldiers had been disarmed and were temporarily housed in a school in Maroua, the capital of Cameroon's Far North region, and about 80 kilometers (50 miles) from the Nigerian border.

Nigeria's military has dismissed suggestions the soldiers fled, and instead found themselves on Cameroonian soil after "a tactical manouevre."

In recent weeks, Boko Haram has claimed to have taken over several towns in Nigeria, where it wants to overthrow the government and create a hardline Islamic state. Cameroonian President Paul Biya has deployed more than 1,000 troops to the Far North to stop Boko Haram from infiltrating Nigeria.

The developments came after Boko Haram leader Abubakar Shekau announced that the group had declared an Islamic caliphate in the northern Nigerian town of Gwoza, in Borno State. The group has been in control of the town for several weeks, with the Nigerian military making attempts to retake it back.

African linguistics expert Norbert Cyffer told DW that inhabitants of Gwoza are fleeing to the mountains in fear.

But the Nigerian government has refuted Boko Haram's claim of a caliphate.

"The claim is empty," Nigeria's defense ministry said on Twitter.

"The sovereignty and territorial integrity of the Nigerian state are still intact."

Thousands of deaths

The militants are accused of killing several thousand civilians across the country's north since 2009, while more than 2,000 have been killed this year alone.

Earlier this year, the group claimed responsibility for the kidnapping of more than 200 schoolgirls from the Borno town of Chibok.

According to the UN, nearly 650,000 have fled their homes in the states of Borno, Yobe and Adamawa, which have been under emergency rule since Nigerian President Goodluck Jonathan launched a military campaign against Boko Haram in May last year.

jr/jm (dpa, AFP)