David Cameron has delivered a wide-ranging speech to the Knesset, addressing every aspect of Britain's relationship with Israel.
The Prime Minister told the Israeli Parliament that he was resolutely opposed to boycotts and delegitimisation, and would steadfastly oppose threats to shechita and Jewish practices in Britain.
Mr Cameron said: "Let me say to you very clearly: with me, you have a British Prime Minister whose belief in Israel is unbreakable and whose commitment to Israel’s security will always be rock solid.
"Delegitimising the state of Israel is wrong. It’s abhorrent. And together we will defeat it."
He said Israeli politicians were free to visit Britain at any time, safe from the threat of prosecution under universal jurisdiction.
Turning his attention to antisemitism and extremism in Britain, Mr Cameron said: "We said no to Zakir Naik. We said no to Yusuf Qaradawi. And we said no to Dieudonne M’bala M’bala whose abhorrent displays of antisemitism have no place in a tolerant and inclusive Britain.
"I've stood up to protect Jewish practices too. The Jewish community has been an absolute exemplar in integrating into British life in every way but integration doesn't mean that you have to give up things that you hold very dear in your religion.
"When people challenged kosher shechita, I have defended it. I fought as a backbench member of Parliament against the last attempt to do something to change this. And there's no way I'm allowing that to change now I'm Prime Minister.
"On my watch Shechita is safe in the UK."
Mr Cameron said the two countries were committed to driving the growth of high-tech start-up businesses, co-operating on technology to protect British and Nato forces in Afghanistan, and on scientific causes.
"To those who do not share my ambition who want to boycott Israel I have a clear message. Britain opposes boycotts," the Prime Minister said.
"Whether it’s trade unions campaigning for the exclusion of Israelis or universities trying to stifle academic exchange Israel’s place as a homeland for the Jewish people will never rest on hollow resolutions passed by amateur politicians."
Mr Cameron urged Israeli leaders to pursue talks with the Palestinians in order to secure a "lasting and secure peace".
He said a deal would bring benefits to all Israelis and their neighbours.
"Imagine what this land would be like if a two-state solution was actually achieved. Think of all the aspects of life that would change.
"Israel’s relationships with the world. Its security its long-term prosperity and the quality of life for all its people.
"On Israel's relationships, imagine, as John Kerry put it: 'Mutual recognition of the nation state of the Palestinian people and the nation state of the Jewish people'. Let's be clear what that means.
"An end to the outrageous lectures on human rights that Israel receives at the United Nations from the likes of Iran and North Korea.
"An end to the ridiculous situation where last year the United Nations General Assembly passed three times as many resolutions on Israel as on Syria, Iran and North Korea put together.
"No more excuses for the 32 countries in the United Nations who refuse to recognise Israel."
Mr Cameron hit back at what he said were those who blame Israel for extremist actions around the world. He said the threat of a nuclear Iran was not caused by Israel.
"There is no rule that says if Israel and the Palestinians make peace, Iran is somehow going to dismantle its despotic regime or abandon its nuclear intentions.
"That can only be done through sustained international pressure. I share your deep scepticism and great concern about Iran. I am not starry eyed about the new regime.
"A nuclear armed Iran is a threat to the whole world - not just to Israel and with Israel and all our allies, Britain will ensure that is never allowed to happen.
"Islamist extremism is a warped and barbaric ideology that ties to set our societies against each other by radicalising young Muslims all across the world."
Ending his address, Mr Cameron pledged to be with Israel "every step of the way".
He told Knesset members: "Later this week you will celebrate Purim.
"You will recall the time when the Jewish people were under threat of extermination in ancient Persia.
"And you will experience a day of joy in memory of the way the Jewish people were saved and freedom was delivered.
"All of us here long for the day that the Jewish people can be free and safe in their homeland.
"I know the challenges in getting there are great. But far greater is the friendship I bring from Britain - and the strength of our collective resolve.
"So as I stand here with you and look to the future, my message to you today is simply this: we'll be with you every step of the way."