North Korea vowed on Tuesday to strengthen its nuclear deterrent and its means of delivery — an apparent reference to missiles — days after threatening rival South Korea and U.S. forces with attack if they conduct military exercises as planned next week.

Pakistan government has no plans to roll back the country's atomic programme and is committed to maintaining a minimum nuclear deterrence, Parliamentary Affairs Minister Babar Awan said on Tuesday.

Resisting Japan's push for signing Comprehensive Test Ban Treaty (CTBT), India on Tuesday made it clear that the onus of taking the lead in this regard lies with the US and China which are yet to ratify the pact.

Iran would be willing to swap nuclear material with the West in Turkey, the foreign minister said in the country's latest counter-offer to a UN-drafted deal aimed at thwarting Tehran's ability to produce atomic weapons.

Iran's nuclear chief said on Friday the country has started making more efficient centrifuge models that it plans to put in use by early 2011 — a statement that underscores Tehran's defiance and adds to international concerns over its nuclear ambitions.

In keeping with the parliamentary demand that obliges the government to limit its cooperation with the International Atomic Energy Agency, from now Iran will not go beyond its legal commitments in interaction with the agency, an Iranian nuclear official said.

Iran accused world powers on Wednesday of trying to spy on the country with a newly built UN seismic monitoring station near its border to detect tremors from nuclear explosions.

Iranian air defence forces began on Sunday five days of manoeuvres involving simulated attacks on the country's nuclear sites, state-owned Press TV and Al-Alam television channels reported.

Iran will begin large-scale air defense war games on Sunday aimed at protecting its nuclear facilities from possible attack, a senior military commander said on Saturday.

Iranian armed forces chief of staff General Hassan Firouzabadi on Friday said he backed proposals for Tehran to ship out most of its stocks of low-enriched uranium in return for fuel for a reactor designed to produce medical isotopes.

Talks between Moscow and Washington to replace a key nuclear disarmament treaty that expires in December have hit a snag over proposed restrictions on Russian missiles, a newspaper said on Thursday.

The US Treasury Department on Friday announced sanctions against the Malaysian subsidiary of Iran's Bank Mellat, which Washington says helps finance the proliferation of weapons of mass destruction.

Russia and the United States on Monday resumed talks on renewing a key agreement on limiting their nuclear arsenals, their envoys in Geneva told AFP.

India and Argentina on Wednesday signed an agreement in civil nuclear cooperation and nine other pacts with a desire to establish strategic partnership.

North Korea said Tuesday it is willing to return to six-nation nuclear disarmament negotiations but only on condition it first holds talks with the United States to improve relations.

While Beijing is Pyongyang's sole major ally and its major trade partner and energy supplier, the North's determination to develop nuclear weapons has strained ties.

A senior US official met Iran's top atomic negotiator for face-to-face talks on Thursday — the first such encounter in years of big-power attempts to persuade Tehran to freeze a program that could create nuclear weapons.

Even as they prepare for new talks on Thursday with Iran on its nuclear programme, the US and its allies are contemplating new and tighter sanctions on Tehran, in a clear signal of expectations that the negotiations may again end in failure.

Iran's nuclear chief said on Tuesday his country built its newly revealed uranium enrichment facility inside a mountain and next to a military site to ensure continuity of its nuclear activities in case of an attack.

Iranian lawmakers warned the US and other world powers on Tuesday against further pressures over Tehran's disputed nuclear program just days ahead of a key international meeting.

Western intelligence puts Iran's newly revealed nuclear plant in the arid mountains southwest of Tehran, not far from one of the holiest cities in Shiite Islam.

President Barack Obama and the leaders of France and Britain said on Friday that the existence of a previously secret Iranian nuclear facility ups the ante on Tehran in international talks next week, declaring that Iran must cooperate on its suspected weapons development "or be held accountable."

India has refused to abide by the UN Security Council resolution asking all non-NPT nations to sign the pact, saying it cannot accept the "externally prescribed norms or standards" on issues that are contrary to its national interests or infringe on its sovereignty.

The UN Security Council on Thursday unanimously adopted a resolution asking all non-NPT states to join the treaty at an unprecedented summit chaired by President Barack Obama who signaled that these countries which included India must come on board.

With US President Barack Obama presiding over an historic session, the UN Security Council unanimously approved a US-drafted resolution on Thursday aimed at ridding the world of nuclear weapons.