Israeli forces were put on heightened alert yesterday after mass protests broke out across the country over the fatal police shooting of a 22-year-old Arab citizen, Khair al-din Hamdan.

Police said that Mr Hamdan had tried to attack officers with a knife in Kfar Kana near Nazareth early on Saturday and “with their lives in danger” had shot him after firing a warning shot.

But the Jerusalem Post posted a video of the incident which showed Mr Hamdan banging on the windows of a police vehicle before retreating from the officer who opened fire as he turned his back.

Thousands took to the streets of Israeli Arab towns to protest over the killing, throwing stones and petrol bombs at police.

Arab Israeli community leaders called a strike yesterday and held demonstrations outside universities and other institutions.

Police spokesman Micky Rosenfeld said that police have beefed up security to its second-highest level — the country’s highest since the conclusion of Israel’s 50-day bloodletting in Gaza.

Prime Minister Benjamin Netanyahu voiced no regret over the police killing of Mr Hamdan.

“Israel is a nation of law. Whoever violates the law will be punished severely. We will not tolerate disturbances and riots,” he blustered.

“I have instructed the interior minister to use all means, including evaluating the possibility of revoking the citizenship of those who call for the destruction of the state of Israel.”

The latest tensions add to those already raging in Israeli-occupied Jerusalem, where Palestinians in the east of the city are protesting over access to the al-Aqsa mosque site.