Zimbabwes ageing President Robert Mugabe on Wednesday criticised ruling party officials for allegedly "bickering" over positions of power and jostling to succeed him.

"Positions in the party are not jumped upon. People rise slowly," Mugabe told members of his Zimbabwe African National Union-Patriotic Front (ZANU-PF) party's central committee.

"So, dirty politics should never be countenanced in our party. The tradition of our party is never one of bickering over party positions," he said in a speech at the ZANU-PF headquarters in the capital Harare.

Mugabe, 92, has been in power since independence from British colonial rule in 1980.

The leader, who has previously been rumoured to be unwell, appeared tired Wednesday as he drawled through parts of his speech, while repeatedly pausing for breath.

Despite his advanced age, Mugabe has avoided naming a successor or laying out plans to retire. He once joked that he would rule until he turned 100.

The absence of a clear successor has sparked infighting in recent years between factions angling for his position, threatening to split the ruling party.

In 2014, Mugabe expelled his deputy Joice Mujuru after Mugabe's wife Grace launched a campaign against the former vice-president, accusing her of instigating factional fighting and plotting to topple the veteran ruler.

Mujuru denied the charges and formed her own party, along with other ZANU-PF former members.

"I have said this before, that there is nothing wrong in expressing an ambition, an aspiration," Mugabe told senior party officials before the meeting.

"But I however frowned upon shameless and unbridled ambition which also seeks to ride roughshod over others."

Mugabe's deputy Emmerson Mnangagwa has been named the leader of a faction seeking to succeed Mugabe.

Another faction, named Generation 40 or G40 because its members are generally younger, reportedly has the backing of Mugabe's wife Grace.

Wednesday's meeting came ahead of the ZANU-PF's annual conference in the town of Masvingo, which runs until Saturday.

The conference is expected to once again endorse Mugabe as presidential candidate.