David Cameron's policy chief Oliver Letwin blamed "bad moral attitudes" for a series of devastating riots which erupted in predominantly black inner city areas in the mid 1980s, newly released government papers have revealed.
Mr Letwin made the remarks in a memo to then Prime Minister Margaret Thatcher, in which he dismissed proposals to foster a new class of black entrepreneurs, saying they would set up in the "disco and drug trade".
His comments, made in the wake of the 1985 Broadwater Farm riots, were labelled "ignorant and deeply racist" by Labour, who demanded an apology.
Mr Letwin has apologised "unreservedly" for any offence he caused.
The files were released by the National Archives in Kew and show that Mr Letwin - then an adviser in Mrs Thatcher's Number 10 policy unit - poured scorn on claims that the disturbances were the product of urban deprivation, saying white communities had endured such conditions for decades without rioting.
The riots which erupted in autumn 1985 were among the worst disturbances to hit mainland Britain in recent years.
They included serious unrest in the Handsworth area of Birmingham and Brixton, south London, as well as the Broadwater Farm riot where Pc Keith Blakelock was stabbed to death.
The troubles were widely blamed on a combination of high unemployment, slum housing, poor education and an atmosphere of bitter distrust between many young black people and the police.
But in a memo to the prime minister, Mr Letwin and Conservative MP Hartley Booth dismissed the prevailing view.
"The root of social malaise is not poor housing, or youth 'alienation', or the lack of a middle class," they wrote.
"Lower-class, unemployed white people lived for years in appalling slums without a breakdown of public order on anything like the present scale; in the midst of the depression, people in Brixton went out, leaving their grocery money in a bag at the front door, and expecting to see groceries there when they got back.
"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."
Plans by environment secretary Kenneth Baker to refurbish crumbling tower blocks or by employment secretary Lord Young to encourage new black middle class entrepreneurs as a "force for stability" were not the answer, they argued.
"David Young's new entrepreneurs will set up in the disco and drug trade; Kenneth Baker's refurbished council blocks will decay through vandalism combined with neglect; and people will graduate from temporary training or employment programmes into unemployment or crime," they told Mrs Thatcher.
The papers were released for the first time on Wednesday under the 30-year rule.
Labour deputy leader Tom Watson called on Mr Letwin, now a Cabinet Office minister, to apologise.
"Oliver Letwin's comments are evidence of an ignorant and deeply racist view of the world," said Mr Watson.
"He obviously cannot justify his opinions but he must explain himself and apologise without delay.
"A great many people will be asking whether, as a Government minister, he still holds such offensive and divisive views."
In a statement, Mr Letwin 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."
Labour MP David Lammy who grew up alongside the Broadwater Farm estate in Tottenham, north London, said the comments were "breathtaking".
"Letwin's statement is an indication of how the powerful can be so utterly, utterly out of touch with what's going on," he said.
The Cabinet Office said the Government at the time had been "proposing solutions to rebuild broken communities".
Officials described the memorandum as a "historical document" written by a policy team whose main task was to challenge "orthodox views".
"We remain thoroughly committed to helping the most vulnerable and ensuring that nobody is confined by the circumstances of their birth," a Cabinet Office spokesman said.