Harare - A group of soldiers was in custody in Zimbabwe on charges of plotting to oust President Robert Mugabe and replace him with a cabinet minister, a newspaper report claimed on Friday.

The paper claims that around six men, including a former army officer and at least two serving soldiers, were currently in custody, some of them since late May. They are being charged with treason.

The men are accused of plotting to overthrow the longtime Zimbabwean leader whose popularity many believe may be finally on the wane - and replace him with Rural Housing Minister Emmerson Mnangagwa, once a favourite of Mugabe.

The Independent says a former army officer spilled the beans on the alleged coup because he feared it would plunge Zimbabwe into chaos.

The army officer travelled to the Zimbabwean embassy in Paris to alert the authorities of the plot, providing them with a map and a list of those involved, the paper alleges.

Mnangagwa, who was shocked in 2004 to be pipped to the post of vice-president by former army commander's wife Joyce Mujuru, told the Independent he knew nothing about that.

"That is stupid. I don't know anything about that. I'm reading about it in the paper but there's nothing like that," he was quoted as saying.

There has been no official comment on the coup plot allegations, which were also carried in a London-based weekly. The state security minister, Didymus Mutasa, has said he knows nothing about it.

But an activist from the opposition Movement for Democratic Change (MDC), Gilbert Kagodora says he was seized by police in Harare as he spoke to a retired army officer.

Kagodora says he was held from May 29 to June 4, when he was beaten and accused of plotting to topple Mugabes government by June 2.

Discontent is rising rapidly in Zimbabwe, where record inflation of more than 3 700% and deepening levels of poverty are making life unbearable for millions.

Unconfirmed reports say soldiers' anger at meagre pay packets has been rising too, and the government may have granted them a significant pay rise last week.