Tehran, Iran - Iran on Thursday vowed to significantly increase its output of enriched uranium in defiance of US demands ahead of a new round of nuclear talks overshadowed by fears of an imminent Israeli attack.

The announcement came after the UN nuclear watchdog – the International Atomic Energy Agency (IAEA) – accused Iran of non-compliance with its obligations, prompting Israel to say the world must respond "decisively."

The US and other Western countries, along with Israel, have repeatedly accused Iran of seeking a nuclear weapon, which it has repeatedly denied.

Ahead of the sixth round of US-Iran talks in Oman on Sunday, the Islamic republic threatened to strike US bases in the region if the negotiations fail and conflict erupts.

Uranium enrichment is a central dispute, with Iran defending it as a "non-negotiable" right in its pursuit of a civilian nuclear program, while the US has called it a "red line."

Iran's foreign minister and chief negotiator, Abbas Araghchi, said the IAEA's resolution "adds to the complexity of the discussions."

"We will be in Muscat to defend the rights of the Iranian people," he said.

The IAEA's board of governors adopted a resolution condemning Iran's "non-compliance" with its nuclear obligations under the Non-Proliferation Treaty (NPT), carried by 19 votes in favor, out of 35 in total, diplomats said.

The resolution could lay the groundwork for European countries to invoke the "snapback" mechanism under the 2015 Iran nuclear deal, reinstating UN sanctions in response to non-compliance – an option that expires in October.

Iran's nuclear chief Mohammad Eslami slammed the resolution as "extremist," blaming it on Israeli influence.

He insisted Iran has upheld its commitments under the NPT but rolled back adherence to the 2015 deal after Donald Trump withdrew the US from the accord during his first term as US president.

"They can't expect us to fulfill them without them (Western countries) honoring any of their commitments," he said.

In response to the resolution, Iran issued a defiant statement outlining its next steps.

"The necessary orders have been issued by the head of the Atomic Energy Organisation (of Iran) to launch a new enrichment centre in a secure location," said a joint statement from the organization and the foreign ministry.

Iran would also replace "all of these first-generation machines with sixth-generation advanced machines" at the Fordo uranium enrichment plant south of Tehran, the organization's spokesman Behrouz Kamalvandi said.

This means "our production of enriched material will increase significantly," he added.

Eslami said enrichment would begin at the new "invulnerable" site "as soon as the machines are installed."

Iran currently enriches uranium to 60%, far above the 3.67% limit set in the 2015 deal and close, though still short, of the 90% needed for a nuclear warhead.