Thabane faces mounting calls to step down from rivals within his ruling party and opposition groups over suspicions he had a hand in the murder of his estranged wife in 2017.

An AFP journalist in the capital Maseru reported that soldiers backed by armoured vehicles had returned to their barracks by Sunday morning after Thabane had deployed them the day before to "restore order" while accusing unnamed law enforcement agencies of undermining democracy.

The spokesman for the army was not immediately available for comment.

A South African envoy has arrived in Lesotho, Thabane's senior private secretary Thabo Thakalekoala told AFP on Sunday.

He did not elaborate but many in Maseru suspect South African President Cyril Ramaphosa had dispatched the envoy to the tiny kingdom surrounded by South Africa in a bid to facilitate talks between Thabane and his opponents.

In power since 2017, Thabane, 80, deployed troops on Saturday a day after the constitutional court overturned his decision to suspend parliament for three months.

The premier has been under immense pressure to step down after the police investigations suggested his involvement in the murder of his late wife, Lipolelo Thabane, three years ago.

- 'Seriously concerned' -

Dropped by his own party, the Convention of all Basotho (ABC), Thabane has promised to retire by the end of July because of his age but the ABC and the opposition demand his immediate departure.

ABC deputy leader Professor Nqosa Mahao said the party was "seriously concerned" that the prime minister was hellbent on misusing security agencies to derail a multi-sector reform process inspired by the South African Development Community.

In a joint statement with opposition groups like the Democratic Congress, Basotho National Party and Popular Front for Democracy, Mahao said "the prime minister's actions clearly points out that he is no longer fit to hold office".

"To protect his own integrity, we therefore advised the prime minister to reconsider and leave office ahead of the time that he had communicated to Basotho."

A highly placed government source said police commissioner Holomo Molibeli, his deputy Paseka Mokete and another senior police officer have been arrested by the army.

The country has been in political turmoil for months.

In March, Thabane imposed a three-month suspension of parliament shortly after the national assembly passed a bill barring him from calling fresh elections if he loses a no-confidence vote hanging over his head.

Last month, he ordered the security forces and intelligence service to probe his ruling All Basotho Convention (ABC) party rivals, whom he accused of plotting to topple his government.