Kamel Ghanem, one of those being held, said the detainees were caught up in a dispute between Mr. Arafat and the Palestinian cabinet headed by Prime Minister Mahmoud Abbas.

"We are being detained right now, but we are refusing to go to jail," Mr. Ghanem, a leader of the militant Aksa Martyrs Brigades, said in an interview on a mobile phone.

The strange episode appeared to reflect divisions among the Palestinian leadership over how to handle negotiations with Israel. Mr. Abbas and members of his cabinet are the ones meeting with the Israelis, who have shunned Mr. Arafat. However, Mr. Arafat has insisted that he have the final say on any negotiations.

Some Palestinians offered an alternative explanation. They said that there were no divisions but that Mr. Arafat was handling this difficult action because the militants were more likely to heed him than Mr. Abbas, who is weak politically.

Israelis and Palestinians have been discussing the proposed withdrawal of Israeli troops who are in or around six main Palestinian cities in the West Bank. The Palestinians want the Israelis out of all the cities, but have emphasized Ramallah. The city is the Palestinian political headquarters in the West Bank and includes Mr. Arafat's compound.

In discussions Wednesday night, Israel said it would not leave Ramallah unless the Palestinians arrested suspected militants and put them in jail in Jericho. That town has been largely quiet during the nearly three years of fighting.

Muhammad Dahlan, the Palestinian security chief, rejected the Israeli demand, according to aides of Mr. Dahlan. He was leading the Palestinian side at the negotiations. 

But on Friday night, Mr. Arafat's office called in about 20 of the suspected militants for a meeting at the Palestinian leader's compound with a plan that largely acceded to the Israeli demand. Some of the militants have been living at the compound to avoid arrest by Israeli security forces, while others have been staying there on and off.

Before the meeting, the men were asked to hand over their weapons and mobile phones, a standard security measure before entering Mr. Arafat's offices, said Mr. Ghanem, though he later managed to obtain a phone. When the meeting began, the suspects were surprised to hear that they were being placed under detention and would be sent to the jail in Jericho, Mr. Ghanem said.

The men protested, he said, and after hours of debate Mr. Arafat agreed to see them at 3 a.m. Mr. Arafat said the Palestinians had already told several foreign governments that the men would be jailed, Mr. Ghanem said.

The detainees continued to protest, he said, telling Mr. Arafat: "Give us 24 to 48 hours to leave the area. We will be responsible for our own security." He said Mr. Arafat rejected the offer.

Most or all of the detainees belong to Al Aksa Martyrs Brigades, which has carried out suicide bombings and shooting attacks against Israel. The group is loosely linked to the Fatah movement, which is led by Mr. Arafat. Mr. Abbas is also a senior figure in Fatah.

Aides to Mr. Arafat could not immediately be reached for comment. However, Palestinian sources said that the detainees were being held by security force members loyal to Mr. Arafat.