LONDON (AP) _ Britain's Defense Ministry has denied that scientists once considered setting off ''an atomic bomb-type explosion'' in Scotland. But it said they had contemplated carrying out tests there which would have released into the atmosphere radioactive materials used in atomic bombs.

Member of Parliament Gordon Wilson of the Scottish National Party had set down a series of formal parliamentary questions to Defense Secretary Michael Heseltine over the Marley report.

This was a scientific paper written in the early 1950s by Dr. W.G. Marley, a scientist at the Harwell Atomic Research Center in England, which was read Monday to an Australian Royal Commission investigating British nuclear tests in Australia between 1952 and 1963. Monday was the last day of the commission's 42-day hearing in London.

Press Association, the British domestic news agency, said the paper showed that scientists had seriously thought of exploding an atomic bomb in the highlands near Wick on Scotland's northeast coast, but decided against it because it rained too much there.

A ministry spokesman, who in accordance with British practice declined to be identified, said later Monday: ''There was a proposal in the 1950s to carry out experiments in the Wick area involving the release of short-life radioactive material: this was polonium ... Polonium releases alpha particles which generate neutrons to start a nuclear reaction going. This was not an atomic bomb-type explosion.''

He said the proposal was scrapped ''as it was decided that Wick was not a suitable site. The chosen location was Emu Field in Australia.''

The spokesman said the proposed tests in Scotland would have involved only the initial ''trigger'' stages of a nuclear explosion. He did not say what degree of explosion would have been involved in these initial stages.

Wilson commented: ''I was staggered to hear that the north of Scotland was considered as a test site ... It tends to support the view of my party that Scotland has been regarded for years as no more than a dispensable province of the United Kingdom.''

The Scottish National Party demands home rule for Scotland. It has two seats in the 650-seat House of Commons.

Commission lawyer Peter McClellan released the Marley document during questioning of Lord Penney, Britain's chief scientist for the Australian tests.

Penney, 75, said that, in hindsight, a 1953 test explosion at Emu in the southern Australia desert should not have been conducted. Fallout from the blast caused radiation sickness in aborigines 100 miles away. He said the test was based on faulty information about weather in the area.