At least 31 types of torture are being used by the Syrian government including electric shocks and male rape, a report has claimed.

The horrific practices were detailed in a study by Amnesty International.

Some of the methods listed in the report include ‘crucifixion’-style beatings, electric shocks, use of pincers on flesh and male rape with broken bottles and metal skewers.

The full report (titled 'I Wanted To Die') describes in gruesome detail the violence endured by opposition fighters and civilians in the 12 months since the uprising began against President Assad's regime.

Dozens of torture survivors were interviewed and spoke of bring arrested and then forced into a hoisted tyre, or suspended on hooks and chains, before being beaten with sticks, rifle butts, whips or braided cables in a process known as "haflet al-istiqbal" or "reception".

One witness, 18-year-old "Karim", a student from al-Taybeh said that interrogators used pincers to remove flesh from his legs when he was being held at an Air Force Intelligence branch in Dera’a.

Another detainee, named "Tareq", said in the report that he was forced to watch another prisoner being raped during his interrogation at the Military Intelligence Branch in Kafr Sousseh, Damascus.

He said: "They pulled down his trousers. He had an injury on his upper left leg. Then the official raped him up against the wall. Khalid just cried during it, beating his head on the wall."

Ann Harrison, Amnesty's interim deputy director in the region, said the report revealed "a nightmarish world of systemic torture".

The Syrian government continues to blame massacres in Homs on "armed terrorist gangs", while denying responsibility for the violence.

Meanwhile Prime Minister David Cameron said ahead of meetings with President Barack Obama that Britain wants to see a transition of power and not a revolution in Syria.

"We're all frustrated by Syria. What's happening in Homs is completely appalling," the PM said. "I'm endlessly kicking the tyres and asking what else can be done."

The violent repression of protests in the Middle Eastern state will be high on the agenda in the round of meetings at the White House on Wednesday.

The Prime Minister and US president will discuss diplomatic and economic measures to increase pressure on the regime of dictator Bashar Assad, but are not thought likely to consider more radical options like arming rebels or air strikes of the kind seen in Libya last year.

Cameron said: "The shortest way of ending the violence is a transition where Assad goes, rather than a revolution from the bottom. Transition at the top rather than revolution at the bottom."

The two leaders are also expected to seek alignment on a timetable for the withdrawal of international troops from Afghanistan, after Cameron acknowledged that the public want to see an "endgame" to a military operation which has now dragged on for more than a decade.

Elsewhere Russia's deputy defence minister said that the country was happy to continue supplying arms and training to the Syrian military.

Anatoly Antonov said on Tuesday: "Russia enjoys good and strong military technical co-operation with Syria, and we see no reason today to reconsider it.

"Russian-Syrian military co-operation is perfectly legitimate," he said.

He added that Russia is currently training Syrian troops in the country.

"It's part of our contractual obligations," the minister said.

The United Nations says that at least 8,000 people have died in Syria after the uprising began almost exactly 12 months ago.