DUBAI (Reuters) - Iran said on Monday it will block snap inspections by the U.N. nuclear watchdog this month if other parties to the 2015 nuclear deal fail to fulfil their obligations, a challenge to U.S. President Joe Biden’s hope of reviving the accord.

“If others do not fulfil their obligations by Feb. 21, the government is obliged to suspend the voluntary implementation of the Additional Protocol,” Foreign Ministry spokesman Saeed Khatibzadeh said.

“It does not mean ending all inspections by the U.N. nuclear watchdog ... All these steps are reversible if the other party changes its path and honours its obligations.”

The Biden administration aims to return the United States to the nuclear deal, which then-President Donald Trump abandoned in 2018. Under the deal, Iran agreed to curbs on its nuclear programme in return for the lifting of sanctions.

After Trump quit and reimposed sanctions, Iran began violating some limits in the deal. Washington and Tehran now disagree over how best to restore the accord, with both sides demanding the other side act first to return to compliance.

The nuclear deal granted wide-ranging access to the International Atomic Energy Agency to gather information on Iran’s nuclear activities. But under a law enacted last year, Iran’s government is obliged to revoke that access on Feb. 21 if other parties are not complying with the nuclear deal.

Iran has long denied seeking nuclear weapons.

Iran’s intelligence minister said last week that persistent Western pressure could push Tehran to fight back like a “cornered cat” and seek nuclear weapons. But Khatibzadeh rejected this, citing a religious decree issued in the early 2000s by the Islamic Republic’s top authority, Supreme Leader Ayatollah Ali Khamenei, banning nuclear arms.

“Iran has not sought and will never seek nuclear weapons ... The Supreme leader’s fatwa is valid,” said Khatibzadeh.