Iran nuclear
File photo of Iranian workers standing in front of Bushehr nuclear power plant Image Credit: Reuters

Iran's top political chamber gave final approval to a bill forcing President Hassan Rouhani to end international nuclear inspections unless the US lifts key sanctions by February, giving the incoming Biden administration just weeks to make a diplomatic breakthrough.

The powerful Guardian Council, a political and legal body made up of senior clerics and scholars, ratified the bill on Tuesday and made it a legal requirement, while extending the deadline for sanctions relief to two months, instead of one, Iranian state TV reported.

That would appear to give Rouhani's government - severely weakened since outgoing U.S. President Donald Trump walked away from the 2015 nuclear deal - barely two weeks after successor Joe Biden enters office to make major strides toward brokering the removal of U.S. oil and banking sanctions.

It's unclear whether the government is able to contest or appeal the Guardian Council's decision. Iran's hardline parliament had fast-tracked the law's passage on Tuesday after Iran accused Israel and the U.S. of killing Mohsen Fakhrizadeh, a top nuclear scientist last week.

Biden has said he wants to reinstate the nuclear deal while Trump has been accelerating his efforts to destroy it before he leaves the White House on Jan. 20. Earlier on Wednesday, Rouhani rejected and criticized the legislation.

"Of course the government does not agree with that ruling and sees it as harmful to diplomatic efforts," Rouhani told a cabinet meeting on Wednesday, the state-run Islamic Republic News Agency reported.

The UN's International Atomic Energy Agency has played down the bill's significance as a domestic matter that has had no bearing on cooperation between Iran and the agency.

Increased tensions over Iran's nuclear program and incidents like the killing of Fakhrizadeh could complicate life for the incoming Biden administration, which has pledged to end Trump's economic offensive against Tehran and re-engage diplomatically.

Iran said on Wednesday that the Ministry of Intelligence had "identified relevant individuals" involved in the assassination, the semi-official Tasnim news agency reported. Israel hasn't commented on the claim it was behind the killing.