North Korea's reported nuclear test poses a "clear threat to international peace and security", Foreign Secretary Margaret Beckett has said.
A robust international response is necessary, says Mrs Beckett
The UN Security Council is considering a draft resolution proposing wide ranging financial and trade sanctions against the country.
And Mrs Beckett told the Commons the UK would be taking a tough approach.
Her Tory shadow William Hague said more international efforts were needed to prevent the spread of nuclear weapons.
Mrs Beckett said the underground test, which reportedly took place in Gilju in Hamgyong province at 1036 (0236 BST) on Monday, jeopardised regional stability in north east Asia.
But she rejected claims the development resulted from a failure in diplomacy.
"This is a course of action they [North Korea] have been pursuing for their own reasons for a long time indeed," she told MPs.
She said the explosion had been big enough to have been a nuclear blast, but that could not be confirmed without the detection of radioactive particles.
"The world has been united in its condemnation of North Korea's action, which was carried out in direct defiance of the will of the international community," said Mrs Beckett.
"The UK will be pushing for a robust response given the clear threat posed to international peace and security by the test."
Mr Hague, the Tory shadow foreign secretary, said the first goal must be to get North Korea to return to its obligations and negotiations.
But there was also a need to strengthen the nuclear non-proliferation treaty as a whole and deal "resolutely" with those who breach it - like North Korea and Iran, he said.
"There is clearly a growing perception in the world that the price of stealing one's way into the nuclear club is bearable. This is a perception we cannot afford to allow to continue," he said.
Liberal Democrat foreign affairs spokesman Michael Moore said he supported the security council's drive to draw up sanctions.
He added: "We stress the need for China and Russia to recognise their responsibilities and to support these measures."
But Mr Moore claimed that agreement would be difficult to achieve while there was even the prospect of US military action which, he said, would be "absolutely catastrophic".