Despite an increase in their numbers in Nablus, Israeli troops regularly conduct security raids there.
"I hope this will be a step in the direction of restoring full [Palestinian] security jurisdiction in these areas," Saeb Erekat, Palestinian negotiator and Fatah member, said.
"So far this has not been done, and if the Israelis continue coming ... to Nablus and Jenin, this would undermine our effort."
Order to chaos
A security official in Jenin told Al Jazeera that the forces would enforce the law, secure safety of the Palestinian people and end all signs of disorder and chaos in the city.
"The security forces will carry out a campaign to impose law and order in the Jenin governorate," General Thiyab al-Ali, commander of Palestinian security forces in the West Bank, said.
"These forces will implement the orders of President Mahmoud Abbas to serve the citizens, protect them, and end the security breakdown in the governorate."
The Jenin campaign will cover 50 villages and is supposed to last three months.
It will be accompanied by a series of economic development projects, officials said.
One Palestinian security source in Jenin said the force would be authorised to enter Jenin's refugee camp and other areas that have been off-limits to Palestinian forces.
Security has improved in Jenin over the last six months as fighters from Abbas's Fatah faction turned in weapons as part of an amnesty programme co-ordinated with Israel.
Washington wants to see progress on security and economic development in the occupied West Bank before George Bush, the US president, visits Israel later this month.
The Jenin deployment also coincides with the arrival of Condoleezza Rice, the US secretary of state, in the region on Saturday.
Washington, whose efforts for a deal on a Palestinian state this year have shown little sign of progress, wants the Jenin campaign to go beyond crime-fighting to combat armed groups - Israel's main condition for implementing the peace agreement.
US-backed peace talks were launched in November with the goal of reaching a deal before Bush leaves office in January.
However, Washington says neither side is doing enough to meet their obligations under a peace road map.
Under the road map, Israel is meant to halt settlement activity and remove Jewish outposts.
The Palestinians are expected to combat armed groups in the West Bank, where Abbas holds sway, and in the Gaza Strip, which is controlled by rival group Hamas.
The Jenin campaign is the second big push by Abbas's forces, whose initial operation launched in Nablus last year was marred by Israeli army raids and travel restrictions.
Israel reoccupied West Bank cities, seven of which had been under Palestinian control after the 1993 Oslo peace accords, after the outbreak of the Palestinian uprising in 2000.
Israel has emphasised that "ultimate security responsibility will remain in Israel's hands" although Western officials note the Jenin area has few iilegal Jewish settlements and checkpoints, reducing the rationale for an Israeli military presence.