Cabinet member Oliver Letwin has apologised “unreservedly” for comments he made about black people in a memo after the 1985 Broadwater Farm riot.

Mr Letwin, currently Chancellor of the Duchy Lancaster, was a 29-year-old advisor to Prime Minister Margaret Thatcher at the time. He blamed the unrest, in which policeman Keith Blakelock was killed, on “bad moral attitudes” in a joint memo, adding that any government assistance given to the black community would end up in the “disco and drug trade”.

The memo - among previously unseen government papers released by the National Archives - showed that in the view of Mr Letwin and his joint author, inner cities adviser Hartley Booth, “the root of social malaise is not poor housing, or youth alienation or the lack of a middle class.

“Lower-class unemployed white people had lived for years in appalling slums without a breakdown of public order on anything like the present scale.

“Riots, criminality and social disintegration are caused solely by individual characters and attitudes. So long as bad moral attitudes remain, all efforts to improve the inner cities will founder.”

Mr Letwin, who is Jewish, and Mr Booth also advised that any communities programme meant to help the situation would simply “subsidise Rastafarian arts and crafts workshops”.

In a statement on Wednesday, Mr Letwin, who has been MP for West Dorset since 1997, said: “I want to make clear that some parts of a private memo I wrote nearly 30 years ago were both badly worded and wrong.

“I apologise unreservedly for any offence these comments have caused and wish to make clear that none was intended.”

The riot in Tottenham and Handsworth took place after north London estate resident Cynthia Jarrett died of heart failure during a police raid of her home in October 1985.

The four policemen said they were looking for stolen property, but found none. As well as the fatal stabbing of PC Blakelock, 230 police officers were injured in the ensuing riot.