Lesotho's prime minister has lost a no-confidence vote in parliament, deepening the political uncertainty in the mountain kingdom ahead of a snap election likely within three months.

The vote on Wednesday against Pakalitha Mosisili, head of a coalition government, came two years after his Democratic Congress (DC) ousted former Prime Minister Thomas Thabane's All Basotho Congress (ABC) by uniting with smaller parties.

Now it is Thabane's ABC that leads a coalition of opposition parties, including the Alliance of Democrats (AD) party, a group that split from DC last year, in an effort to remove Mosisili.

Members of parliament voted in favour of replacing Mosisili with AD's Monyane Moleleki.

"The vote of no confidence motion to urge His Majesty King Letsie III to appoint Honourable Monyane Moleleki as the next prime minister has been carried.