Palestinian authorities carried out their first executions since 2002 on Sunday, killing four convicted murderers in a campaign meant to halt a growing wave of lawlessness but which drew swift condemnation from human rights groups.

The executions reflected the tough challenge that Palestinian leader Mahmoud Abbas (search) faces as he tries to impose law and order in the Palestinian areas. Abbas has made public order a top priority, but his forces have been severely weakened by internal rivalries, a lack of resources and years of fighting with Israel.

Despite Abbas' efforts to revamp his security forces, militant groups and armed gangs continue to operate with virtual impunity, often clashing with rival factions or police.

In a fresh challenge to Abbas, two Islamic militant groups responsible for dozens of bombings threatened Sunday to pull out of a four-month-old cease-fire, accusing Israel of violating the truce. Leaders of Hamas (search) and Islamic Jihad (search) said they would make a final decision in the coming days.

"It looks like Israel will continue in this aggression and we cannot accept that anymore," said Mohammed al-Hindi, an Islamic Jihad leader.

The truce has brought a drop in violence, although sporadic fighting has persisted. Abbas met with the militants in Gaza last week in a bid to shore up the truce after several days of violence that included a deadly Palestinian rocket attack and Israeli arrest raids in the West Bank.

Sunday's executions appeared to be an attempt to deter criminals and send a message to the public without directly confronting the militants. None of the executed men was believed to be affiliated with any of the major militant groups. Their crimes date to the mid-1990s.

"There is a new policy of enforcing the law, to face and fight the chaos and lawlessness in the Palestinian territories," Interior Ministry spokesman Tawfiq Abu Khoussa said.

Abu Khoussa said Abbas signed the execution orders Saturday. Three of the men were hanged, and the fourth was shot by firing squad, in line with the sentences handed down at their trials.

There was no advance notice of the pre-dawn executions, which had been approved by Islamic authorities.

The executions follow a new wave of internal violence in the Palestinian areas. Gunmen have clashed with Palestinian security forces in Gaza at least three times in recent days.

Even after the executions, the unrest continued in the bustling West Bank town of Ramallah, where a feud between two families escalated from a fistfight into a shootout. While no one was injured by gunfire, the officials said the shooting caused public panic.

The Palestinian Authority has had the death penalty in place since its establishment in 1994. However, the late Palestinian leader Yasser Arafat halted the death penalty in 2002 after criticism by European countries and international human rights groups.

The Gaza Center for Human Rights, a Palestinian monitoring group, said the executed men were all serving murder sentences in Palestinian prisons. The men were common criminals.

Rigi Sorani, chairman of the human rights group, condemned the killings and accused the Palestinian Authority of carrying out a "token" execution that failed to go after the gunmen and rogue elements of the security forces responsible for much of the recent violence.

"When we learned about President Abbas planning to carry out executions three months ago, we sent him a letter, and I personally met with him to talk him out of it," Sorani said.

Including Sunday's killings, the Palestinian Authority has executed 13 people.

The Israeli human rights group B'tselem, which spends most of its time documenting alleged abuses by Israel against the Palestinians, also condemned the killings and urged Abbas to halt further executions.

One of the executed men was convicted and sentenced by a special security court — which have been criticized for lack of due process — just a week after the crime in September 2000, according to the Gaza human rights group.

Some 47 Palestinians remain on death row, about half of them convicted collaborators with Israel. Palestinian officials said last month they had suspended plans to execute the collaborators, fearing their deaths would inflame tensions with Israel.

Israel has put heavy pressure on Abbas to crack down on militants, saying peace talks cannot resume until he reins in the gunmen.

On Saturday, Palestinian Foreign Minister Nasser Al Kidwa said Palestinian security forces would not disarm militant groups so long as Israel's occupation of the West Bank and Gaza Strip continues.

Israeli officials responded by accusing Al Kidwa of destroying chances of renewing peace talks.

"Very simply, either they will fight terrorism or we will fight terrorism," Israeli Vice-Premier Ehud Olmert told Israel Radio.

Until now, Abbas has refused to confront the militants with force. Instead, he has tried to persuade them to lay down their weapons in exchange for jobs and a role in Palestinian decision-making.

Among Abbas' concerns is ensuring an orderly and peaceful transition in the Gaza Strip after the Israeli withdrawal scheduled in August. With Israeli hard-liners opposed to the pullout, Israel wants to avoid clashes with Palestinians during the evacuation.