BOSASSO (Reuters) - Somali security forces said on Sunday they had killed 18 Islamist insurgents during an operation in the northern region of Puntland, although the militants denied sustaining any casualties.

“We killed 18 militants and burnt six of their bases in Galgala hills in an operation over four days to eliminate al Shabaab,” said Colonel Mohamed Ismail, a senior officer in the Puntland Security Force.

“We also took their weapons. We burned their food and medicine stores.”

Puntland’s security forces are trained and supported by a small number of U.S. operatives based in the semi-autonomous northern region. It was not clear whether the United States had any involvement in the operation.

Al Shabaab, an al-Qaeda-linked insurgent group that wants to impose strict Islamic law, confirmed there was a raid but denied there were any casualties.

“Puntland attacked us today but we repulsed and chased them away. No casualties at all,” Sheikh Abdiasis Abu Musab, the spokesman for al Shabaab’s military wing, said by phone.