Britain will work "flat out" and keep "all options on the table" in order to prevent Iran from developing a nuclear bomb, foreign minister Liz Truss vowed on Monday.
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.
"We are absolutely determined to prevent Iran from securing a nuclear weapon," she added.
Iran said it hoped to reach an agreement with major powers on salvaging its 2015 nuclear deal at talks resuming in Vienna on Monday.
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".
The pair said earlier in a joint article in the Daily Telegraph newspaper they would "work night and day to prevent the Iranian regime from ever becoming a nuclear power".
The landmark 2015 nuclear deal offered a lifting of some of the economic sanctions Iran had been under, in return for strict curbs on its nuclear programme.
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).
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