Thatcher, who became Britain's first female premier in May that year, had to decide early on her premiership a policy on what to do about the thousands of people fleeing Communist-ruled Vietnam.

Many of them paid to leave on overcrowded boats for Hong Kong, British-ruled at the time, which was taking around 400 people a day in 1979.

The United Nations and charities urged countries including Britain to step in and resettle more Vietnamese, but Thatcher privately countered their arguments in colourful terms.

Britain did eventually admit 10,000 people from Vietnam.

But Thatcher was quoted as saying: "There would be riots in the streets if the government had to put refugees into council houses" by the official record of a discussion she had with her foreign and home secretaries on June 14 1979.

She aired more protests the following month in a discussion on the issue with the same ministers, Lord Peter Carrington and Willie Whitelaw.

After one noted that he had received many letters from members of the public on the issue, Thatcher suggested: "All those who wrote letters in this sense should be invited to accept one (a Vietnamese refugee) into their homes," the official record said.

"She thought it quite wrong that immigrants should be given council housing, whereas white citizens were not."

Thatcher also said that she would rather admit refugees than immigrants to Britain and "with some exceptions, there had been no humanitarian case for accepting 1.5 million immigrants from South Asia and elsewhere."

The files also reveal an early sign of her loathing of far-left ideology.

On top of a diplomatic summing up of the situation in Vietnam in June 1979, an official wrote: "An appalling assessment" and Thatcher wrote next to it: "Yes - that is Communism".

The documents were released by the National Archives in London under the 30-year rule. This allows classified government files to be made public after three decades.

Agence France Presse - December 30, 2009