Prime Minister Rishi Sunak has met Benjamin Netanyahu at Downing Street as the Israeli leader faces domestic turmoil over judicial reforms.
Mr Sunak greeted Mr Netanyahu outside Number 10 ahead of talks over security and the threat from Iran.
He is also due to meet Home Secretary Suella Braverman on his one-day visit.
Meanwhile, hundreds of protesters gathered at the gates of Downing Street to demonstrate against Mr Netanyahu's policies.
A cacophony of noise could be heard, including shouts of "shame" and "traitor", as the Israeli PM made the short walk from his convoy to the steps of Number 10.
A planned photo opportunity for the gathered media was cancelled, the Jerusalem Post newspaper reported, and there was no joint statement.
The visit comes at a time of political turmoil in Israel, with the country gripped by months of some of the biggest demonstrations in its history.
Mr Netanyahu has defied calls to scrap moves to shake up the legal system, amid warnings the crisis is not only causing social upheaval but could harm Israel's security with growing numbers of military reservists refusing to serve in protest.
Thursday saw tens of thousands of Israelis take to the streets across the country, in scenes which have been repeated weekly and escalated since the start of the year.