Palestinian leader Mahmoud Abbas fired the top West Bank security chief Saturday and said he would retire hundreds of senior officers, serving notice of a shakeup of security forces long demanded by the United States.

Abbas had been criticized for not moving fast enough to reform his flabby security apparatus, seen as largely ineffective in reining in Palestinian militants. Saturday's decision sent the strongest signal since Abbas took office in January that he is serious about cleaning house. The Palestinian Authority (search) has 45,000 to 50,000 security officers on its payroll.

"We will not allow anyone to take the law into his own hands and sabotage our situation," Abbas said, criticizing the security services for not doing their job.

The international community, led by the United States, has long demanded that the Palestinians streamline their corruption-plagued security forces, which under the late Yasser Arafat (search) ballooned into nearly a dozen rival branches with often overlapping authorities.

Abbas had come under growing pressure at home to take action after gunmen shot up his offices and rampaged through Ramallah (search) on Wednesday.

The gunmen were loyal to West Bank security chief Ismail Jaber (search), who was relieved of his command Saturday. The local security chief in Ramallah, Younis Al-Aas, was also dismissed.

In a meeting with about 50 intellectuals, religious leaders and business people Saturday evening, Abbas said the gunmen had used the government compound, known as the Mukataa (search), for more than four years "to commit crimes and to come back to it."

Arafat had sheltered more than two dozen militants, many of them wanted by Israel, in the Mukataa. Some of the gunmen were mainly involved in attacking Israelis, while others also engaged in extortion, kidnapping and other violence against Palestinians.

"I want to distinguish between nationalists and criminals," Abbas said in remarks broadcast on Palestinian TV. "The security apparatus did not perform its duty, so it was crucial to take a stand," he added in his most blunt criticism yet of the security forces.

It was not immediately clear who would replace Jaber, an Arafat crony who had been West Bank security chief since the Palestinian Authority was created in 1994.

Israeli media mentioned Jibril Rajoub (search), Abbas' national security adviser, as a possible successor. However, Palestinian officials said they did not know whether Abbas had picked a replacement.

Rajoub once headed the powerful Preventive Security Service (search) in the West Bank, but fell out with Arafat over how to handle the conflict with Israel. Rajoub opposed using weapons against Israel and largely kept his men on the sidelines during the past four years of fighting.

Abbas also announced Saturday that he would enforce a recent law requiring security personnel to retire at age 60. At least 2,000 top and middle-level security officers, many throwbacks to the Arafat era, would be forced out, paving the way for a new generation to take over, security officials said.

A committee has already identified hundreds who will be sacked, one official said on condition of anonymity.