UK will work 'flat out' to stop Iran becoming nuclear power
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Truss met her Israeli counterpart Yair Lapid for talks in London on Monday, where he will also meet with Prime Minister Boris Johnson.
Truss made the comments in a press briefing shortly after signing a "memorandum of understanding" aimed at creating stronger collaboration between the two nations on cyber-security, defence and trade.
She said Britain would "work flat out to prevent the Iranian regime from gaining nuclear weapons.
Truss said that Britain "wants those talks to work, but if they don't work, all options are on the table".
But Lapid accused Tehran of trying to get sanctions lifted.
"They will play for time, earn billions from the removal of sanctions, continue to deceive the world, and covertly advance their nuclear programme," he said.
"This is what they have done in the past and it is what they will do this time as well.
"The world must prevent this, and it can prevent this," he added, calling for "tighter sanctions (and) tighter supervision".
But the deal began falling apart in 2018 when then-US president Donald Trump pulled out and began reinstating sanctions.
The following year, Iran retaliated by exceeding the limits on its nuclear activity laid down in the deal and has in recent months restricted the activities of inspectors from UN watchdog the International Atomic Energy Agency (IAEA).