LONDON: Police on Thursday arrested a dual UK-Iranian national on suspicion of plotting a terror attack following a security incident at a US-run military air base in England that British authorities have linked to Tehran.

The 27-year-old man was arrested in London on Thursday, and police have searched two properties in the UK capital, Counter Terrorism Policing said in a statement.

A 26-year-old British national was interviewed by police “under caution,” which means the interview was recorded and can be used in future prosecutions.

On Sunday, five men, all British nationals in their 20s and from London, were arrested on suspicion of explosives and terror offenses close to the RAF Fairford air base, which has been used by American bombers to strike Iran. The suspects have since been released on bail.

Police say they found a quantity of an accelerant – gasoline – in three vans linked to the five suspects, but no explosives.

Vicki Evans, the senior national coordinator for counter terrorism policing, said the investigation “is hugely complex, and our specialist teams are interrogating multiple lines of inquiry.

“As we’ve made clear, we’re looking at all possible angles — including possible foreign state involvement,” she said.

Prime Minister Andy Burnham has said the UK sees “strong indications” that Iran played a part in the incident. Iran denies involvement.

The comments led Iran to summon the British ambassador to Tehran, Hugo Shorter, according to the Iranian official IRNA news agency.

Iran’s deputy foreign ministry denounced the British government’s “baseless accusations” and condemned the country for making military bases and facilities under its jurisdiction “available for the planning and execution of the US-Israeli military aggression against Iran.”

Israeli Prime Minister Benjamin Netanyahu, speaking to Fox News late Wednesday, said Israel tipped off Britain about a plot shortly before Burnham’s government on September 8 announced sanctions on products from Israeli settlements in the occupied West Bank.

“You want to hear how absurd things are there, and how far the anti-Israel propaganda has gone?” Netanyahu told the US network’s conservative host Sean Hannity.

“We gave the Brits the intel that there was going to be an attack, and it’s an Iranian-sponsored attack. And pretty much the next day, they slapped sanctions on us,” he said.

Netanyahu has spent decades warning of threats from Iran’s cleric-run state, sometimes meeting skepticism elsewhere.

US President Donald Trump earlier spoke of a possible Iranian role in the incident, in which a resident reported masked men near vans heading to the Fairford air base.

The base 100 miles (160 kilometers) west of London has been used by American bombers during decades of conflicts in the Middle East, including this year’s war with Iran.