Robert Mugabe has lost his grip on power and been replaced by his wife, Grace Mugabe, Zimbabwe’s opposition leader has claimed.

Morgan Tsvangirai said that the 91-year-old president’s wife is now effectively in charge after a "palace coup”, and that the government has been paralysed as members of the ruling party jockey for position.

"No one in government is thinking of solutions to the national challenges as everyone is preoccupied with issues of who will succeed this tired man steering the ship of state,” Tsvangirai was quoted by South Africa’s Mail and Guardian newspaper as saying.

Grace Mugabe has been an increasingly prominent presence on Zimbabwe’s political scene in recent months, taking up a key post in the ruling party last December and going around the country addressing rallies and handing out gifts.

Her aggressive statements against those she deems insufficiently loyal to her husband come at a time when Africa’s oldest leader is looking increasingly frail.

The famously austere Mugabe has long been in robust physical and mental condition, but several mishaps in recent months have sent tongues wagging.

Bodyguards had to rush to stop him from falling as he stumbled while reaching out to shake hands with Indian Prime Minister Narendra Modi in the last week of October. A month earlier, he read the wrong speech during the opening of parliament without realising his error.

Mugabe is still expected to be endorsed as the ruling party Zanu-PF’s presidential candidate in 2018, when he will be 94.

But with the end of his rule inevitably drawing nearer, a furious behind-the-scenes succession battle is underway.

Local media have reported two competing camps forming around army chief Emmerson Mnangagwa and Grace Mugabe, despite president Mugabe’s warnings that the jockeying for power "threatens to split the party”.

Amid this battle, Tsvangirai’s claim that Robert Mugabe wife had "surreptitiously but willingly” assumed power appear designed to take advantage of the current rifts.

Grace Mugabe has managed to rally a group of younger party members around her, dubbed by local media as "the G-40”, but she is generally unpopular with the wider public thanks to her lavish shopping trips overseas at a time when the country’s economy is struggling to recover from a devastating period of hyperinflation.

On Tuesday, Zimbabwe announced it would make the Chinese Yuan legal tender, as one of a basket of currencies that replaced Zimbabwe’s own dollar, which was abandoned in 2009 with inflation running at 500bn%.

This is a copy of the original article by The Guardian (UK).