Israeli security forces have stepped up searches for gun suppliers in the occupied West Bank they say are behind an upsurge in shooting attacks in Jerusalem, officials said Sunday.

"There's an increase in operations... trying to find where they're made," police spokesman Micky Rosenfeld told AFP after the Shin Bet domestic security service announced the discovery of a cache of firearms in the West Bank.

"There are joint operations, coordination to prevent those types of weapons coming in. They're obviously coming in from the West Bank."

A Shin Bet statement said that in a joint operation with the army on Friday it found 15 locally produced weapons stored in the village of Yabad, near the northern West Bank town of Jenin.

It also said that on March 1 in the city of Nablus, Israeli forces seized several weapons and lathes used in arms production.

Violence in Israel and the Palestinian territories since October has killed 190 Palestinians and 28 Israelis.

Most of the Palestinians were killed while carrying out knife, gun or car-ramming attacks, Israeli authorities say.

Others were shot dead by Israeli forces during clashes or demonstrations, while some were killed in air strikes on Gaza.

On February 3, next to the walls of Jerusalem's Old City, three Palestinians armed with rifles, knives and explosives attacked Israeli police, killing a policewoman and wounding another before being shot dead.

In a similar incident in the same area, on February 14 two Palestinians opened fire on police without causing casualties before being shot dead by officers.

On Tuesday, just before a visit by US Vice President Joe Biden, a Palestinian shot and seriously wounded two Israeli police officers with an automatic weapon on a busy east Jerusalem street. He was shot dead.

The next day there was more gunfire in the city when two Palestinians fired at a bus then fired shots near the Old City. One person was wounded, but it was unclear whether he was hit by police or assailant gunfire.

The two Palestinians were killed by police.

"In the past few weeks we've seen automatic weapons, which we hadn't seen before," Rosenfeld said.

He called it "a change of phase and that's something we are dealing with at the moment".

However, Rosenfeld and a senior military officer who briefed journalists on condition of anonymity Sunday said no organised militant group was behind the violence.

Most of the attackers, many of them young people, are believed to have acted on their own.

Many analysts say young Palestinians are fed up with the Israeli occupation, while Israel blames incitement by Palestinian leaders and media as a main cause of the violence.

"For the most part there are no strong networks producing arms and originating complex attacks," the army officer said.

"At the end of the day it is about the decision of this or that lone wolf..."