The rift between Somalia's prime minister and president is intensifying with the latest sacking of security minister.

Prime Minister Mohamed Roble sacked the minister late Wednesday but President Mohamed Abdullahi "Farmajo" rejected the move.

Mr Roble replaced Security Minister Hassan Hundubey Jimale with Abdullahi Mohamed Nur.

President Farmajo on Thursday said the move was unconstitutional.

This is the second time the prime minister and president are differing on appointments.

The prime minister last weekend sacked the spy chief and the president reinstated him then later appointed him on a new role.

This was after the spy chief defied the order to produce a comprehensive report on the disappearance of a spy agent in 48 hours.

The two leaders have in the past differed publicly on policies.

President Farmajo banned agreements with foreign entities until after elections but the prime minister went ahead to sign agreements in his Kenya visit last month.