Zimbabwe's President Robert Mugabe has been re-appointed as leader of the ruling party, while his wife Grace has been given a top position in the party.

Grace Mugabe's promotion to head of Zanu-PF's women's wing puts her in a good position to succeed her husband in the future, analysts say.

The first lady has criticised political rivals, including Vice-President Joyce Mujuru, in recent months.

Mr Mugabe, 90, is due to stand for election again in 2018.

Speaking at Zanu-PF's congress, Mr Mugabe thanked thousands of supporters for choosing him as party leader.

"I know where I come from... I am not greater than the people who gave birth to me," Mr Mugabe, who has led Zimbabwe since 1980, said.

Assassination allegations

The first lady's appointment as head of the women's wing is seen as a further sign that Mrs Mujuru, who was once seen as a potential successor to Mr Mugabe, has been sidelined.

Mrs Mujuru fought alongside Mr Mugabe for Zimbabwe's independence from white-minority rule.

However, her career ran into trouble when Mrs Mugabe, 49, entered politics this year, and accused the deputy of plotting against her husband.

Speaking to the congress on Thursday, Mr Mugabe described Mrs Mujuru as a corrupt thief, and said she had planned to assassinate him.

He said he welcomed the fact that his wife had exposed Mrs Mujuru's attempt to oust him.

However, recently expelled Zanu-PF member Rugare Gumbo told the BBC that Mr Mugabe had targeted Mrs Mujuru to advance the "fortunes" of his wife.

The congress also gave Mr Mugabe the power to appoint his deputies - increasing his control over the party.

Mr Mugabe told supporters that he would announce a successor to Mrs Mujuru later this week, AP news agency reported.

With Mrs Mujuru's fall from grace, there is speculation that Justice Minister Emmerson Mnangagwa will be given a top position.