MAIDUGURI, Nigeria (Reuters) - About 20 Nigerian soldiers are missing after a clash with Boko Haram militants in the northeast of the country, security sources said on Monday, though the military denied reports that some troops could not be found.

FILE PHOTO: A Nigerian army convoy vehicle drives ahead with an anti-aircraft gun, on its way to Bama, Borno State, Nigeria August 31, 2016. REUTERS/Afolabi Sotunde/File Photo

The confrontation between militants and troops took place on Saturday in the Bama area of Borno, the state worst hit by the jihadist group which has killed more than 30,000 people since 2009 when it launched an insurgency to create an Islamic caliphate.

Three soldiers told Reuters more than 20 were missing.

“We lost some of our soldiers in the attack. It is possible those missing are dead. We haven’t seen about 23 of them now,” said an officer who did not want to be named.

Another soldier involved in the clash said the troops were ambushed while conducting a “clearance operation”, adding that “over 20 soldiers have not been seen up till now”. He said five military vehicles were taken.

The militant group carries out suicide bomb attacks in crowded places, such as markets, as well as gun raids and attacks on military bases.

At a news conference on Monday, the military said media reports of the soldiers being missing were untrue.

An army spokesman said suspected Boko Haram militants had tried to seize military vehicles in an attempted attack on troops in Bama but they had been repelled by troops backed by the air force.

“About 22 members of Boko Haram terrorists were neutralized while several others escaped with gunshot wounds. Efforts are being intensified by the troops to get the fleeing members of the Boko Haram terrorists,” said a military spokesman.

Boko Haram held territory around the size of Belgium in northeast Nigeria for several months until being pushed off much of that land in early 2015 by Nigeria’s army and troops from neighboring countries.

Bama, about 60 km (40 miles) southeast of Borno’s state capital Maiduguri, was held by Boko Haram from September 2014 until March 2015.

Nigeria’s government has said since December 2015 that Boko Haram has been “technically defeated”. Yet attacks continue in the northeast while another group, an Islamic State ally that split from Boko Haram in 2016, holds territory.