asked the Prime Minister if he will make a statement about Her Majesty's Government's present policy with regard to on-site inspection of seismic events of suspected nuclear origin, in relation to the extension of the nuclear test ban treaty to include underground nuclear explosions.
The hon. Gentleman will see that that matter is dealt with in the Answer which I propose to circulate. When I was in Moscow, and my noble Friend was in Moscow shortly afterwards, we pressed on the Russians the idea of scientific exchanges to test some pilot explosions to see who was right about this. I am afraid that so far they have not agreed to joint policing tests of this kind.
If the hon. Member is referring to a relatively small underground explosion, although it is possible to identify a great number of them because of the improvement in seismic detection, it is not possible finally to say that a particular explosion is of a nuclear character or may be due to natural causes. That is our view. The Soviet Government take a different view. That is why I should like the scientists to get together to argue it out.
I think that the ventilation engineers will note what the hon. Member has said and the undertones behind it.
Following is the information:
The major obstacle to a comprehensive test ban treaty is that although we can detect by seismic means all underground events of importance we cannot be sure in every case whether they are earthquakes or not. Although there
have been recent improvements in seismic detection capability, we cannot foresee any scientific progress that will ever enable us to close this gap.
In recent years the Soviet Government have resolutely refused to agree to on-site inspections as a means of identifying suspected nuclear tests. We are seeking with our allies ways of overcoming this difficulty, and the non-aligned nations at the Eighteen Nation Disarmament Committee have made suggestions which we are examining. We are particularly studying the Swedish suggestion for verification by challenge, and in the proposal for a ban on only those tests above a certain seismic magnitude.