Israel has been stepping up its military offensive in the West Bank, a day after Israeli Prime Minister Ariel Sharon declared Palestinian leader Yasser Arafat an enemy and said Israel was at war.
Troops have moved into the towns of Qalqilya and Tulkarm, where several Palestinian suicide bombers originated from, and tanks are poised on the edge of Bethlehem.
The city of Ramallah, under siege for four days, is now a closed military zone, with troops ensuring Mr Arafat's headquarters are off-limits to journalists.
As the Israeli action was being stepped up, a bomb exploded in central Jerusalem, although without causing the heavy casualties of recent Palestinian militant attacks.
The blast happened as an Israeli policeman flagged down a suspect car for a security check, killing the bomber and destroying the car, the city's police chief said.
The Israeli army is now in full control of Tulkarm after tanks rolled in, backed by helicopters, on Monday afternoon.
The town had been home to the suicide bomber who blew himself up in a hotel in Netanya last week, killing more than 20 people.
Late on Monday evening, several loud blasts and heavy machinegun fire were heard near Mr Arafat's compound in Ramallah, the French news agency AFP reported.
Soldiers have been sweeping through Ramallah to search for suspected militants and have so far detained 700 people, an Israeli army spokesman said.
"We are looking for wanted people who are hiding in private buildings, in apartments...We know they are hiding in official buildings...There are some who are hiding under Arafat's wing," Brigadier-General Ron Kitrey said.
With the city under curfew, Ramallah's residents say they are running out of food.
Medical supplies are also low in the hospitals and the morgues are full because it is impossible to transport bodies to burial grounds.
Mr Sharon says the Israeli actions are aimed at eliminating once and for all what he calls the terrorists' infrastructure.
But his Foreign Minister, Shimon Peres, in an apparent criticism of government strategy, said on national television that Israel should "ease the siege" on Mr Arafat because it had "polarised media attention."
"We must not deceive ourselves. We cannot resolve the problem in one fell swoop, this is very complicated," Mr Sharon said.
Journalists are now banned from the Palestinian leader's headquarters. The BBC's Barbara Plett, who is in Ramallah, says the ban prevents Mr Arafat from making defiant statements to the media that make him look more like a hero than a defeated leader.
The Foreign Press Association has protested strongly against the expulsion of an American television crew from Ramallah and has called on Israel to respect press freedom.
"Closing an entire city to the media indefinitely is an extreme and unjustified policy that makes it impossible for us to cover the important story unfolding here," the FPA statement said.
Around 500 foreign activists are in the West Bank, peace groups say, in an attempt to halt the violence and protect Palestinians.
At least five foreigners and a Palestinian cameraman were injured in Beit Jala near Jerusalem when Israeli troops opened fire during a pro-Palestinian solidarity demonstration.
The foreigners, reported to be from Australia, France, Japan, Britain and the US, were taking part in a march in Beit Jala under the slogan "Peace not war".
But an Israeli army spokesman said the demonstrators had deliberately provoked the soldiers.
"We know for sure that it was an act of provocation carried out on purpose by members of groups supporting terrorists, supporting suicide bombers, killing our women and children," said Lieutenant-Colonel Olivier Rafowicz, quoted by the French news agency, AFP.
As Israel tightens its grip on Palestinian areas, those accused of collaborating are in increasing danger.
Masked Palestinian gunmen have shot dead 11 suspected collaborators to prevent their escape as the Israeli army rolls in.
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