MOGADISHU Jan 24 (Reuters) - At least four soldiers were killed and five wounded on Tuesday when a roadside bomb that Islamist insurgents said they planted exploded outside a military camp in a town near Mogadishu, officials said.

The blast in Afgoye, about 30 km (18 miles) southwest of the capital, took place a day after the al Shabaab group carried out a raid in the same town that was repulsed by government troops, Major Osman Abdulle, a police officer, told Reuters.

"Last night, we repulsed the militants who attacked us. They must have planted the bomb," he said.

Al Shabaab, which has been waging an insurgency across Somalia, claimed responsibility for the bombing. The group is fighting to topple the Western-backed government in Mogadishu.

"We planted the bomb last night. At least seven soldiers died," Sheikh Abdiasis Abu Musab, the group's military operations spokesman, told Reuters.

(Reporting by Abdi Sheikh and Feisal Omar; Writing by Aaron Maasho; editing by John Stonestreet)