Yaounde, April 13 -- At least nine separatist fighters have been killed in clashes in war-torn Cameroon's English-speaking region of Northwest, according to local security sources.

On Saturday, separatist fighters attempted to attack a military outpost in the region, but soldiers repelled the assault, killing four of them and injuring many others, an army official told Xinhua on condition of anonymity late Saturday.

On Friday, security forces ambushed and attacked a group of separatist fighters in the region, killing five of them, according to the official.

Separatist leaders said on social media that a commander was among those killed by the military and vowed to retaliate.

The Cameroonian army has been intensifying its offensive a...