Lesotho's Prime Minister Thomas Thabane, 80, is to be charged with the murder of his estranged wife Lipolelo Thabane, police have said.

Mr Thabane announced he would be stepping down in July because of old age, without commenting about the case.

His current wife Maesaiah Thabane has already been charged with the murder.

He would be the first leader in southern Africa to be charged with murder while in office, in a case that has shocked the tiny mountain kingdom.

Lipolelo, 58, was shot dead two days before Mr Thabane became prime minister in 2017.

At the time, he described her killing as "senseless" but police now accuse him of being involved in her killing.

"The prime minister is going to be charged with the murder," Deputy Commissioner of Police Paseka Mokete was quoted by Reuters news agency as saying.

"The police are preparing directives and he will probably be charged tomorrow [Friday]," he added.

What does the prime minister say?

Mr Thabane said on state radio that he had served the nation "diligently" and he would retire at the end of July, Reuters reports.

"I've worked for a peaceful and stable Lesotho. Today... at my age, I have lost most of my energy," he was quoted as saying.

The ruling All Basotho Convention had given him a deadline of Thursday to resign.

How did the murder take place?

Lipolelo was gunned down at close range on the side of a dirt road while returning to her home in a small village on the outskirts of the capital, Maseru.

She was involved in bitter divorce proceedings with Mr Thabane when she was killed.

At the time, the prime minister was living with Maesaiah, 42, as if she were his wife.

But Lipolelo had already won a separate legal battle to be recognised as first lady, as opposed to Maesaiah.

Maesaiah accompanied Mr Thabane to his inauguration, following his estranged wife's death.

Two months later she and Mr Thabane got married in a Catholic ceremony held at a packed stadium in Maseru.

Maesaiah was charged with her rival's murder on 5 February and is out on bail of about $67 (£52).

She has also been charged with the attempted murder of a family friend Thato Sibolla, who was with Lipolelo at the time of the shooting and is expected to be a key witness in the murder case.

Maesaiah has not yet been asked to enter a plea.