SEOUL (AFP/Reuters) - A defiant North Korea vowed Saturday to build more nuclear bombs and to start enriching uranium for a new atomic weapons programme after the UN Security Council imposed sanctions for its nuclear test. The North, describing Fridays sanctions resolution as a vile product of a US-inspired campaign, said it would never abandon nuclear weapons and would treat any attempt to blockade it as an act of war. It also threatened military action if the United States and its allies tried to isolate it. The 15-member Council voted unanimously Friday to slap tougher sanctions on the North to cripple its nuclear and ballistic missile programmes. The hardline communist state, in a Foreign Ministry statement reported by its official news agency, said all new plutonium it extracts would be weaponised. One third of used fuel rods from the Yongbyon reactor have so far been reprocessed into weapons-grade plutonium, it said. Secondly, we will start uranium enrichment, it said in its first admission that it has such a programme a second route to a nuclear bomb. It has become an absolutely impossible option for the DPRK (North Korea) to even think about giving up its nuclear weapons, the statement said, adding that any attempted blockade would be considered an act of war and met with a decisive military response. It added: No matter how hard the US-led hostile forces may try all sorts of isolation and blockade, the DPRK, a proud nuclear power, will not flinch from them. While UN chief Ban Ki-moon said the resolution sent a clear and strong message to North Korea, US ambassador to the UN Susan Rice said it would be no surprise if Pyongyang reacted to this very tough sanctions regime in a fashion that would be further provocation. US intelligence officials believe it will respond with a third atomic test, according to sources quoted by American TV networks. Giving her reaction, US Secretary of State Hillary Clinton said Norths provocative actions were deeply regrettable and Washington would vigorously impose new UN sanctions against the Stalinist state and to do all we can to halt Pyongyangs nuclear proliferation. We intend to do all we can to prevent continued proliferation by the North Koreans, Hillary told reporters at Niagara Falls on the Canadian side of the border with the United States. The North Koreans, she said have now been denounced by everyone. They have become further isolated. And it is not in the interests of the people of North Korea for that kind of isolation to continue. In Lecce, Italy, finance ministers of the Group of Eight wealthy countries said they were committed to the effective and timely implementation of financial measures against North Korea as set out in the Security Council resolution. We endorse the FATFs (Financial Action Task Force) call for countries to protect the financial system from illicit financing and implement counter-measures against Iran, in particular to mitigate the risk posed by correspondent relationships with Iranian institutions, the statement added.