LONDON (Reuters) - Israeli Prime Minister Benjamin Netanyahu urged “responsible nations” to join new sanctions against Iran on Monday during a visit to London, but Britain defended a nuclear deal sealed between major powers and Tehran.

Britain's Foreign Secretary Boris Johnson (L) greets Israel's Prime Minister Benjamin Netanyahu at the Foreign Office in London, February 6, 2017. REUTERS/Kirsty Wigglesworth/Pool

Ahead of his talks with British Prime Minister Theresa May, Netanyahu said other nations should follow new U.S. President Donald Trump’s imposition of sanctions against Iran following a ballistic missile test.

“Iran seeks to annihilate Israel. It seeks to conquer the Middle East, it threatens Europe, it threatens the West, it threatens the world. And it offers provocation after provocation,” Netanyahu told May ahead of their meeting.

“That’s why I welcome President Trump’s assistance of new sanctions against Iran. I think other nations should follow suit, certainly responsible nations. I’d like to talk to you about how we can ensure that Iran’s aggression does not go unanswered.”

May’s spokeswoman said the British leader had repeated her backing for the nuclear deal with Tehran - which is strongly opposed by both Netanyahu and Trump - but said there was a need to “rigorously monitor” Iran’s behavior.

“The prime minister made clear that we support the deal on nuclear that was agreed,” the spokeswoman told reporters, when asked whether Britain was considering joining new sanctions.

“What happens now is that (the nuclear deal) needs to be properly enforced, and we also need to be alert to Iran’s pattern of destabilizing activity in the region.”

Earlier the spokeswoman said May would also tell Netanyahu that continued Israeli settlement activity in occupied lands captured in the 1967 Middle East War on which the Palestinians hope to create independent state undermined trust in the region.

“STRONG AND CLOSE ALLY OF ISRAEL”

Despite their differences, London has adopted a more positive approach to Israel since May became leader after last year’s vote to leave the European Union, echoing the more sympathetic tone set by Trump, with whom Britain wishes to secure a post-Brexit trade deal.

May told Netanyahu that Britain was a “strong and close friend of Israel”, and highlighted their co-operation in science, trade and security.

They agreed to set up a working group to develop trade ties both before and after Brexit, the spokeswoman said.

Last month Britain said it had reservations about a French-organized Middle East peace conference in Paris and did not back the final communique by 70 countries which reaffirmed that only a two-state solution could resolve the Israeli-Palestinian conflict. Its stance angered many EU members.

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In December, Britain also scolded then U.S. Secretary of State John Kerry for a speech criticizing Israeli policy.

Netanyahu’s talks on Monday got off to an awkward start as he arrived before May was at her official Downing Street residence to greet him. Having entered her office alone, he came back outside minutes later for the customary handshake.

Small groups of pro-Palestinian and pro-Israeli protesters gathered outside Downing Street and Jeremy Corbyn, leader of Britain’s opposition Labour Party, said May’s stance on settlements was not good enough.

“Theresa May must make clear to the Israeli prime minister that the British government will stand unequivocally behind the rights of the Palestinian people,” said Corbyn, who once described members of Palestinian group Hamas and Lebanon’s Hezbollah as friends in comments he later said he regretted.