asked the Lord President of the Council and Minister for Science, in view of the facts that 10 out of 51 underground nuclear test explosions in the United States of America have led to radioactive clouds in the atmosphere and that a further 15 have led to limited leaks of radioactive elements, if he will make a statement on the dangers involved in underground tests.

As regards events in the United States, I would refer the hon. Member to the reply given him by my right hon. Friend the Foreign Secretary yesterday. The facts are not as stated by the hon. Member and there is no danger in the United Kingdom from underground tests.

But did not yesterday's statement admit that five explosions in the year ending August 1962 had released radioactivity which was detected outside the test area, and that in the last fifteen months two other events at Nevada were also detected off site? Will the right hon. and learned Gentleman therefore ask the Prime Minister to respond to the announcement this morning that the Soviet Government are willing to add nuclear underground tests to the existing Test Ban Treaty?

I am sure that the whole House will wish to add a fourth dimensional test ban if the question of verification were satisfactorily negotiated. But I must still tell the hon. Gentleman that he is basing his questions upon facts which are not accepted by the bulk of responsible opinion in America.