Israeli armed forces and border police used the cover of the war against Hamas in Gaza to reintroduce the firing of .22 rifle bullets - as well as the extensive use of a new model of tear-gas canister - against unarmed demonstrators in the Occupied West Bank protesting at the building of Israel's "separation wall".

The tactics were highlighted on Friday, when a US protester, Tristan Anderson, 38, was hit in the head by one of the new extended-range gas canisters in the village of Ni'ilin, suffering an open wound in his skull and substantial brain damage. Anderson's friend, Gabrielle Silverman, claims he was struck by a canister fired from a high-velocity rifle. The Israeli military says stone-throwing "poses a threat to troops", and several officers have been injured by rocks.

It said troops used the permitted means of riot dispersal in Friday's incident, including tear gas, rubber-coated steel pellets and stun grenades.

The extended-range canisters have been brought into service at the same time that the Israeli Defence Force (IDF) and border police have again been using live rounds fired from Ruger sniper rifles, banned in 2001 by Israel's then military advocate general, Menahem Finkelstein.

The new gas canister that injured Anderson - the fourth member of the International Solidarity Movement to be killed or seriously injured by Israeli troops since the beginning of the Second Intifada - is fired at a much higher speed than the gas canisters and grenades deployed before.

According to witnesses, soldiers have been firing the canisters directly at protesters, sometimes from a few dozen metres, using the hard plastic-coated metal tubes as a weapon.

"They have introduced new weapons," said Sasha Solana, a colleague of Anderson from the International Solidarity Movement. "They are shooting directly into people."

B'Tselem, an Israeli human rights organisation, complained to the Israeli judge advocate general two weeks ago about the new tactics.