By Stephanie Busari BBC News

As a former SAS officer, Simon Mann will be used to surviving in the toughest of conditions.

Mann was rearrested shortly after his release from prison last year

But he will need that military training to prepare for life at Equatorial Guinea's Black Beach Prison.

Situated on the tropical volcanic island of Bioko, the jail has been accused of widespread abuse and torture of prisoners.

Mann is being sent there after extradition from Zimbabwe.

He is facing charges of plotting a coup in the tiny country in sub-Saharan Africa and is accused of being the leader of a group of alleged mercenaries.

In 2005, Amnesty International reported that inmates at Black Beach were in danger of starving to death, surviving on daily rations of a cup of rice and one or two bread rolls.

'Life-threatening'

In the same year, the US state department also described conditions at the prison in the capital, Malabo, as "life threatening".

We are locked alone in our cells most of the time while other prisoners go out to the exercise yard and get fresh air Nick du Toit, Black Beach prisoner

However, the old rat-infested building was demolished last year and a new wing built in its place.

A Mail on Sunday reporter who visited the new facility said that Black Beach now had "clean and spacious cells in a newly rebuilt prison complete with a hospital wing and well stocked pharmacy".

Authorities say this renovation means conditions have improved.

However the tiny country has one of Africa's worst human rights records and access to the newly built prison has been restricted.

Mercenaries

A planned visit by a United Nations human rights expert to Equatorial Guinea was cancelled after the government postponed it, citing "urgent activities".

A UN special rapporteur on torture, Manfred Nowak, issued a statement voicing "strong regret" about the postponement of the long-planned trip.

Mann, 55, was arrested when his plane, loaded with 61 alleged mercenaries and military equipment, landed at Zimbabwe's Harare airport in March 2004.

He was accused of trying to buy arms as part of a plot against Equatorial Guinea President Teodoro Obiang Nguema, and sentenced to seven years in jail.

He was re-arrested after his release in Zimbabwe last May.

One of the alleged plotters, the German national Gerhard Eugen Nershz, died a few days after being taken to Black Beach.

The authorities said he had contracted cerebral malaria.

He was taken to hospital from the prison some hours before his death and witnesses claimed that he appeared to have severe injuries on his hands and feet.

An opposition activist, Weja Chicampo, who was arrested at the same time, said later he had been so badly beaten he could not eat properly.

He claimed he was left in handcuffs without water so he had to drink his own urine.

Some of those accused of working with Mann to overthrow the government of the oil-rich country are already serving long sentences there.

Former South African commando Nick du Toit is serving 34 years for his part in the alleged plot.

He said in a recent interview: 'It feels like I've been here my whole life. We are locked alone in our cells most of the time while other prisoners go out to the exercise yard and get fresh air.

'Severely restricted'

"We don't have families living locally to bring us money or food so we can't buy any luxuries, even toothpaste.

"We cook our own food, mostly just rice, on a gas ring on the landing.

"That's the only area we are allowed to move around in. We were given grey and white striped prison uniforms but we can't wear them because we are shackled."

Amnesty International said family visits at the prison have become "severely restricted".

"Currently visiting time is restricted to 15 minutes or less each month. If lots of people come to visit at that time, then the guards would restrict the amount of time each person has with a visitor," a spokesman said.

"In the past, families were allowed to take food into the prisoners.

"This has now been stopped and the food is provided by the authorities but Amnesty doesn't know much or how good the food is for the prisoners.