Portugal suspends visas to Iranians over 'security concerns'

"We suspended them for security reasons," Santos Silva told a parliamentary committee without giving further details, the Lusa press agency reported.

"I will provide an explanation but not in public for security reasons," he said.

"Portugal does not play around with entries into its national territory."

The decision comes amid fraught relations between Iran and Western nations in a number of areas.

Iran and the United States have been engaged in a war of words since Tehran in recent weeks enriched uranium past the limit set by a landmark 2015 nuclear in response to Washington pulling out last year.

There has also been tension on the high seas, after the British Royal Marines helped Gibraltar authorities detain an Iranian tanker that US officials believe was trying to deliver oil to Syria in violation of sanctions.

In response Tehran has issued a series of increasingly ominous warnings to both the US and Britain about its right to take unspecified actions in reprisal.

And France has expressed concern about the fate of a French-Iranian academic arrested in Iran, the latest in a long list of dual nationals held in the country's prisons.

The detention of Fariba Adelkhah, a prominent researcher in anthropology and social sciences based at Sciences Po, risks increasing tension between Paris and Tehran at a critical moment in the crisis over the Iranian nuclear programme.

Adelkhah's arrest comes as France and its EU allies are seeking to keep alive the 2015 nuclear deal on Iran's nuclear programme after President Donald Trump pulled the United States out of the accord unilaterally.

On Monday, Iran’s atomic energy agency said it could reverse its nuclear programme to its status before curbs were imposed under a landmark 2015 agreement with world powers.

"If the Europeans and the Americans don't want to carry out their duties... we will decrease our commitments and... reverse the conditions to four years ago," agency spokesman Behrouz Kamalvandi said, quoted by IRNA state news agency.

"These actions are not out of obstinacy. It is to give diplomacy a chance so that the other side come to their senses and carry out their duties," he added.

The deal promised economic benefits and sanctions relief to Iran, but US President Donald Trump withdrew from the accord in May 2018 and reimposed tough punitive measures against the Islamic republic.

Angered that its beleaguered economy is not receiving sanctions relief it believes it was promised under the deal, Iran has intensified sensitive uranium enrichment work.

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