Obama's grandfather was tortured by Brit officials reveal secret documents

A collection of secret documents detailing efforts to suppress the Mau Mau uprising has revealed that US President Barack Obama''s grandfather and others were brutally tortured by British officials.

The documents, which have lain hidden in the Foreign and Commonwealth Office, in London, for 50 years, were removed from Kenya on the cusp of independence, the Daily Mail reported.

They were uncovered in January after five Kenyans launched a lawsuit against the British government.

The claimants said they suffered castration, sexual abuse, and severe beatings in detention camps administered by the British government, and want an apology and financial compensation.

Obama''s grandfather Hussein Onyango Obama was rounded up in 1949 in the very early days of the rebellion and spent two years in a high security prison.

Once a cook for a British officer, his family claim Obama was horrifically tortured, whipped every morning and evening until he confessed.

His third wife Sarah Onyango said white jailers would squeeze his testicles with parallel metallic rods and pierce his nails and buttocks with pins.

Obama, whose involvement with the rebellion has never been clear, was left permanently scarred and bitterly anti-British.

His account tallies with the experiences of the five elderly Kenyans now suing the British government.

The claimants, represented by law firm Leigh, Day and Co, say they were "subjected to gross abuse and torture".

The crux of their case due to open on Thursday, relies on the premise that the bloody campaign was not isolated incidents but systematic abuse sanctioned by the authorities.

This, they will argue, would make the current British government liable.

The Mau Mau rebellion is widely regarded as one of the worst episodes in British colonial history.

As many as 150,000 suspected members of the resistance movement, which had its roots in the Kikuyu tribe, were detained without trial between 1952 and 1960.

At least 12,000 were killed with thousands more left with deeply debilitating physical and mental injuries.