About 200 soldiers deployed a year ago to bolster security in Lesotho after the killing of the country's army chief have left, a regional official has told the AFP news agency.

Lt Gen Khoantle Motsomotso, and two officers guarding him, were shot dead at a military barracks in the capital, Maseru, in September 2017.

The landlocked country, surrounded by South African, has a history of instability marked by coups or attempted coups.

The mission from the Southern African Development Community (Sadc) was deployed to help "strengthen peace and security", the regional bloc's spokeswoman Barbara Lopi told AFP.

"There is significant improvement in the working relations amongst the various security agencies, the government and civil society," she said, adding that the mission was now complete.