Men thought to be undercover Israeli policemen who had infiltrated a group of Palestinian stone throwers shot and wounded three of them, one seriously, in the West Bank Wednesday.

The incident occurred during clashes with Israeli security forces at the Bet El checkpoint near Ramallah witnessed by AFP.

Four masked men, one carrying a flag of the Islamist movement Hamas, were throwing rocks when others among them suddenly drew pistols. As the infiltrators grabbed and beat one man, they opened fire as stones flew at them.

One of the Palestinians was hit in the back of the head.

Israeli soldiers who were only metres (yards) away rushed in to assist the shooters.

The wounded, two of whom were roughed up by their assailants and the soldiers, were taken away in ambulances.

The Palestinians regularly accuse Israel of placing Arabic-speaking infiltrators among demonstrators in order to make arrests.

Tuesday's incident occurred as unrest has spread in recent days, prompting fears of a wider Palestinian uprising.

Israel's government recently announced a series of new security measures, with Prime Minister Netanyahu declaring "war" on stone throwers and easing rules for when police can open fire.