DUBAI (Reuters) -Britain, France and Germany denounced threats against the head of the U.N. nuclear watchdog on Monday, after a hardline Iranian newspaper said IAEA boss Rafael Grossi should be tried and executed as an Israeli agent.

"France, Germany and the United Kingdom condemn threats against the Director General of the IAEA Rafael Grossi and reiterate our full support to the Agency and the DG in carrying out their mandate," said a statement from the three countries' foreign ministries.

"We call on Iranian authorities to refrain from any steps to cease cooperation with the IAEA. We urge Iran to immediately resume full cooperation in line with its legally binding obligations, and to take all necessary steps to ensure the safety and security of IAEA personnel," they added.

The statement did not specify what threats had been made against Grossi, but it follows an article in Iran's hardline Kayhan newspaper, closely associated with Supreme Leader Ayatollah Ali Khamenei, which accused Grossi of ties to Israel's Mossad intelligence agency. Should Grossi enter Iran, he should be tried and sentenced to death, it said.

Grossi has not directly responded to the newspaper's allegations. He has said his top priority is ensuring IAEA inspectors can return to nuclear sites in Iran as soon as possible.

Iranian officials have not publicly endorsed the newspaper article. Iran's ambassador to the United Nations, Amir Saeid Iravani, denied that there was any threat against Grossi.

But Iran has increasingly criticised Grossi and threatened to halt cooperation with the IAEA, which Tehran blames for providing a justification for Israel's bombing, which began the day after the IAEA board voted to declare Iran in violation of obligations under the Nuclear Non-Proliferation Treaty.

Iran's President Masoud Pezeshkian told French President Emmanuel Macron in a phone call on Monday that the IAEA's "double standards" had created problems for regional and global security, Iranian state media reported.

"The view of the Iranian government, parliament, and people is that the IAEA director has not acted impartially in relation to our country's nuclear file, despite all the cooperation and interactions that have taken place, and this behaviour is in no way acceptable to us," the reports quote Pezeshkian as saying.

Foreign Minister Abbas Araqchi has said Grossi is not welcome in Iran, having carried out "malign action" and played a "regrettable role".

Iran also said on Monday it could not yet be expected to guarantee the safety of IAEA inspectors.

"How can they expect us to ensure the safety and security of the agency's inspectors when Iran's peaceful nuclear facilities were attacked a few days ago?" Foreign Ministry spokesperson Esmaeil Baghaei told a news conference.

Baghaei said an Iranian parliamentary bill calling for the government to withdraw cooperation with the IAEA had been approved by the Guardian Council, a security body controlled by appointees of the supreme leader, and was now mandatory.

"Iran shouldn't be expected to accept its obligations under the nuclear Non-Proliferation Treaty when the U.N. nuclear watchdog has stopped short of condemning the attacks on Iran's nuclear sites," Baghaei said.

(Reporting by Dubai Newsroom and Sudip Kar-Gupta;Editing by Alison Williams and Peter Graff)