Tony Blair has said that the claimed test-firing of a nuclear weapon by North Korea was a "very, very serious" development.
The Prime Minister said the regime in Pyongyang was in "clear breach" of its international obligations.
He urged the regime to return to international talks aimed at resolving the issue of its nuclear weapons programme.
He told reporters in Downing Street: "It is a very, very serious situation. We are discussing it with key allies."
Speaking at a joint news conference with Indian Prime Minister Manmohan Singh, Mr Blair welcomed the "strong stand" taken by China.
"The tragedy of North Korea is not just this nuclear test, which is worrying for all the very obvious reasons, it is what is happening in the country," he said.
"Its people literally are living in oppression, mass poverty and starvation in some cases, while they spend billions of dollars on nuclear weapons and it is a tragedy.
"The only way of dealing with it is through a revitalisation of the Six Party talks and to make sure North Korea comes back into compliance with its international obligations."
Mr Blair rejected "completely false" comparisons between North Korea's nuclear capability and that of the UK and Western allies.
"The difference is that we are a democracy, we abide by the rule of law, we abide by our international obligations. North Korea is doing none of these things."
Read More
MORE ABOUT