Tony Blair, the Labour leader, used measured language, clearly mindful of Anglo-French relations. Speaking in Belfast, he said: "I wish our government had joined with other governments right across the political spectrum in expressing regret at this action. There is no evidence that there is any military justification for it at all. It sends out the wrong signal at a time when we are trying to prevent the spread of nuclear weapons across the world ... The British government must explain why it continues to remain silent, given the world-wide anger."
The Labour leader was supported by the Liberal Democrats. Menzies Campbell, the party's foreign affairs spokesman, said: "This test is scientifically unnecessary and politically inept. It's done great damage to the cause of nuclear non-proliferation."
Mr Campbell wrote to John Major in July urging him to "use every endeavour to persuade the French government not to proceed", and Liberal Democrat and Labour Euro-MPs joined the boycott of French President Jacques Chirac's address to the European Parliament.
The Liberal Democrats will hold an emergency debate at their conference in Glasgow in 10 days' time on a motion put forward by Matthew Taylor MP, the environment spokesman, which "calls upon the British government to condemn the French government's decision".
Labour's environment spokespeople, Frank Dobson and Joan Ruddock, have, however, maintained a strikingly low profile, reflecting the relatively low priority accorded to green issues by "New Labour". Apart from Mr Blair, condemnation of the test has been led by Robin Cook, the foreign affairs spokesman, and David Clark, defence spokesman.
The Conservatives, meanwhile, have held out against pressure to join in condemnation of the French nuclear tests. But Malcolm Rifkind, the Foreign Secretary, this week hinted that he hoped France would carry out fewer than the planned eight tests. "Obviously the French government will want to listen carefully to the expressions of concern that have been expressed in various parts of the world," he said in Ankara, Turkey.
A spokesman for John Major said: "Our priority is getting agreement on the Comprehensive Test Ban Treaty, which France supports."
Britain was one of the few countries in Europe where the French tests drew no criticism from the Government. Germany - France's closest European partner - was also keen not to antagonise Paris and the government there kept its comments to a minimum; although the opposition was highly critical. The opposition Social Democrats put forward a motion calling for the test series to be stopped. And the SPD party manager Guenter Verheugen said Chancellor Helmut Kohl's criticism was "so quiet it could hardly be heard on the other side of the Rhine".