(Adds president quote, updates death toll)
OUAGADOUGOU, Dec 16 (Reuters) - A dozen soldiers were killed in northern Burkina Faso when unidentified gunmen attacked a military post near the border with Mali, President Roch Marc Christian Kabore said on Friday, calling the assailants "forces of evil".
Attacks in Burkina Faso were relatively rare before a major attack by al Qaeda-linked fighters on a hotel in the capital, Ouagadougou, that killed 29 people in January.
"This attack demonstrates that the fight against terrorism will be without respite and also underscores the necessary decisions that must be taken to give confidence and vitality to our army," Kabore said.
He said those killed were members of the army's special anti-terrorist group. The army had earlier said that 10 soldiers and one gendarme had been killed.
Islamic militants are active in Burkina Faso's northern neighbour, Mali, and Burkinabe authorities are concerned the long desert border between the two countries could become a transit point for militants.
Friday's attack about 30 km (19 miles) from the Malian border began around 5 a.m. (0500 GMT) and was carried out "by about 40 heavily armed individuals who have not yet been identified," the army said in its statement.
A newly formed militant group led by a fighter formerly loyal to Algeria's Mokhtar Belmokhtar claimed to have attacked a Burkinabe military position in September, and unidentified gunmen killed three Burkinabe soldiers and two civilians in October. (Reporting By Mathieu Bonkoungou; Writing by Aaron Ross and Joe Bavier; Editing by Matthew Mpoke Bigg/Larry King)