A snapshot of the tension between Britain and America over the supply of guns to Northern Ireland police has been disclosed in Government documents made public for the first time.

Despite only being a few months into her stint as Prime Minister, Margaret Thatcher pulled no punches in her dealings with President Jimmy Carter and the Governor of New York Hugh Carey.

The US government refused to grant an export licence for Ruger revolvers which were intended for use by the Royal Ulster Constabulary in July 1979.

The Americans did not want to take sides in the conflict in Northern Ireland, and efforts were being made to stop US money flowing into IRA coffers.

Mr Carey proposed a meeting between British and Irish officials in New York to discuss the situation, but was subjected to a blistering rebuff by Mrs Thatcher.

A note of a conversation between the Prime Minister and Northern Ireland Secretary Humphrey Atkins on August 23, 1979 was among documents released by the National Archives under the 30-year rule.

It said: "She was not in the habit of discussing the internal problems of the US with the Americans and they should not attempt to do so with us.

"The Americans must be made to realise that for so long as they continued to finance terrorism, they would be responsible for the deaths of US citizens (as had happened in the Hilton Hotel explosion in Belfast) as well as others. They must realise that while this went on, the British Government would attack and condemn them.

"The UK should not be perpetually on the defensive; Governor Carey had already got away with a great deal so far as UK public opinion was concerned. The Americans must be brought to face the consequences of their actions."

Another section said: "The Prime Minister said that Governor Carey could come to the UK if he wished to do so: but Northern Ireland was part of the United Kingdom and she herself would not think of discussing with President Carter, for example, US policy towards their black population."