Large areas of the West Bank city of Nablus were put under curfew overnight Sunday by Israeli troops that poured into the city in jeeps and armoured vehicles.
The troops conducted house-to-house searches and made arrests in what is considered the largest military operation in the West Bank in months.
The military warned people to remain indoors, and took control of local television and radio stations as part of the virtual lockdown. Palestinian residents said troops told them the measures would last for several days.
There have been no deaths related to the operation so far, with just two soldiers and several Palestinians suffering minor injuries in the clashes.
Israeli troops began moving into the city -- the largest in the West Bank and the region's economic centre -- at about 3 a.m., Palestinian witnesses told AP. The convoy included about 80 military vehicles and several bulldozers.
The bulldozers were used to erect huge piles of rubble to serve as barricades on main roads, witnesses said. The main entrance to the city was also closed.
The operation focused on Nablus' Old City, a densely populated area of narrow alleyways, apartment buildings and markets.
The campaign, according to an Israeli military spokesman, was intended to counter terrorist threats in Nablus. It came just one day after the Israeli army discovered a bomb making laboratory in the city, which is known to be a stronghold for militants.
The Israeli operation comes at a sensitive time for relations between the two sides, however, as Palestinian President Mahmoud Abbas tries to piece together a unity government with the radical movement Hamas, and restart peace talks with Israel.
Last week, Abbas held a rare three-way meeting with Israeli Prime Minister Ehud Olmert and U.S. Secretary of State Condoleezza Rice.
Palestinians say the new Israeli action threatens the efforts, even though little progress has been made so far.
"We condemn this military incursion," said Saeb Erekat, a confidant to Abbas. "This will undermine the efforts that are being made to sustain the cease-fire with Israel."
With files from The Associated Press
