Iranian-linked terrorist cells are reportedly thought to be ready to strike the UK as tensions in the Gulf rise.

The cells are operated by people with links to the Lebanese militant group Hezbollah, an Iranian ally, The Telegraph reported.

Multiple Conservative members of Parliament accused the government of having "dropped the ball" by failing to protect UK ships.

Prime Minister Theresa May is expected to chair an emergency meeting on Monday morning as she attempts to deal with the crisis.

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LONDON — Iranian-linked terrorist cells are reportedly thought to be ready to strike the UK if the crisis between London and Tehran escalates further, as supporters of Prime Minister Theresa May's government increased their criticism over Iran's seizing of a British-flagged tanker in the Persian Gulf.

UK intelligence agencies believe that Iran has organized and funded terrorist sleeper cells across Europe and could approve attacks in response to the crisis in the Gulf should it escalate further, The Telegraph reported Sunday night.

The cells are operated by people with links to the Lebanese militant group Hezbollah, an Iranian ally. Counterterrorism police identified a cell in 2015 that was stockpiling large amounts of explosives just outside London.

May is due to chair a meeting of the British government's emergency Cobra committee on Monday in her last week as prime minister, while Foreign Secretary Jeremy Hunt is expected to make a statement in the Commons on Monday afternoon.

The meeting comes after members of the Iranian Revolutionary Guard boarded the Stena Impero on Friday as it passed through international waters, saying it was a "reciprocal action" after British forces intercepted an Iranian tanker near the British territory of Gibraltar at the entrance to the Mediterranean earlier this month. The UK suspected the Iranian tanker of taking oil to Syria in violation of sanctions.

The UK government on Sunday faced allegations from its own members of Parliament and supporters of failing to act sufficiently to guard its shipping in the Gulf, with the seizure of the Stena Impero widely seen as an avoidable incident for which ministers had plenty of warning.

"I take the view that we have dropped the ball here," Conservative MP Huw Merriman, a parliamentary aide to Chancellor Philip Hammond, said on Sunday. "We knew from 4 July, having seized an Iranian tanker that we suspected was breaching EU sanctions and heading for oil to Syria, that there would be some form of reprisal and that's exactly what we've got."

"It was hardly a surprise when one of ours got taken," he told the BBC's "Westminster Hour" on Sunday.

Iain Duncan Smith, the former Tory leader, called it "a major failure" and said the government had "to answer that charge very quickly indeed."

Adding to the criticism, the junior defense minister, Tobias Ellwood, said government cuts to defense funding had left the Royal Navy too small to manage Britain's interests across the world.

Criticism mounted further on the weekend when it was reported that the government rejected the offer of US naval protection for British tankers passing through the Strait of Hormuz, which is near Iranian waters.

Hunt, who is likely to be beaten by Boris Johnson in the leadership race to replace May as prime minister this week, is under intense pressure to join US-led plans for an international maritime protection force in the Gulf.

Allies of Johnson — who is said to be ready to sack Hunt as foreign secretary if he wins the leadership race by a landslide — said the government urgently needed to address the charge that it had made errors in not doing so.

Smith, who is chairing Johnson's campaign, said questions needed to be answered about the UK's planning after it seized an Iranian tanker on July 4.

"If something didn't send an alarm signal that we needed to have serious assets or protection and convoying of our vessels in that area, then I want to know why not," he said.

He added that he had been informed by sources in Washington that the UK had been invited "to use US assets to support British shipping and they were not taken up at that point."