The wife of Zimbabwean President Robert Mugabe has sued a Lebanese businessman for failing to deliver a $1.35-million diamond ring she ordered for her wedding anniversary, state media reported Wednesday.

"First lady Dr Grace Mugabe is suing fugitive businessman Mr Jamal Joseph Ahmed for $1.23 million (1.05 million euros) over a diamond ring deal that went sour last year," The Herald newspaper said.

"In breach of the agreement, Mr Ahmed failed to deliver the ring, triggering a legal wrangle."

In 2015, Grace Mugabe placed an order for a 100-carat diamond ring worth $1.35 million to mark the anniversary of her wedding to the 93-year-old leader.

"The plaintiff wanted to purchase a unique diamond ring for her wedding anniversary celebrations," said court documents seen by The Herald.

"The defendant tendered a diamond ring worth $30,000 and naturally, the plaintiff refused to take possession of an inferior ring."

Grace Mugabe demanded a refund but Ahmed paid back just $120,000.

In court documents filed last year, Ahmed said he had offered to repay the money in instalments and claimed he had already paid back $150,000.

In January Ahmed went to court to stop Grace Mugabe from seizing his properties over the diamond ring spat.

Grace Mugabe has however denied attempting to seize Ahmed's properties, saying police had been guarding his premises because he was wanted for alleged crimes.

The Lebanese businessman holds a Zimbabwean permanent residence permit, but no longer lives in southern African country.

Ahmed also claimed to have received threats from officials from Zimbabwe's spy agency -- the Central Intelligence Organisation -- as well from Grace herself and a son from her first marriage, Russell Goreraza. She has denied the allegation.

Grace, 52, married Mugabe in 1996. She now heads the ruling ZANU-PF party women's league.

She has said that she has the right to rule the country like any other Zimbabwean and is now seen to be among those manoeuvering to replace her husband.