(reuters) -- Troops from the Iraqi army and Popular Mobilization Forces (PMF) were taking part in the campaign against militants hiding in a large strip of border land, Iraqi military officials said.

"The objective behind the operation is to prevent remaining Daesh groups from melting into the desert region and using it as a base for future attacks," said army colonel Salah Kareem.

Iraqi Prime Minister Haider al-Abadi said on Tuesday Isis had been defeated from a military perspective but he would only declare final victory after Isis militants were routed in the desert.

Iraqi forces on Friday captured the border town of Rawa, the last remaining town under Isis control, signalling the collapse of the group's "caliphate" proclaimed after it overran much of Iraq's north and west in 2014.