RAMALLAH, West Bank - Backing down in the face of widespread protests, Yasser Arafat replaced his cousin as Palestinian security chief Monday and asked the former chief to return to his job, Palestinian officials said.

The Palestinian leader phoned Brig. Gen. Abdel Razek Majaide and asked him to return to the office he left last week at Arafat's request, said Nabil Abu Rdeneh, a senior Arafat adviser.

Arafat took the decision to calm the anger that has spilled into the streets of Gaza over the appointment of Moussa Arafat, Rdeneh said. Opponents claimed the appointment perpetuated a system of corruption and cronyism endemic among the Palestinian leadership.

But Moussa Arafat retained a senior security post in Gaza, subordinate to Majaide who has overall authority in both Gaza and the West Bank, the officials said.

On Sunday night, Palestinian gunmen stormed an intelligence office in one Gaza refugee camp and marched through another, protesting Moussa Arafat's appointment.

But in Gaza City today, hundreds of his supporters marched through the streets, some firing assault rifles into the air - raising the possibility of a violent conflict over the appointment.

"We will protect you by our soul and our blood, our hero Abu Amr," the demonstrators chanted, referring to Yasser Arafat.

The turmoil in Gaza was a grave challenge for Arafat and highlighted sharp rifts between the veteran Palestinian leader and the Cabinet that is supposed to be running the West Bank and Gaza Strip.

Dozens of masked gunmen marched near Moussa Arafat's office in the Nusseirat refugee camp in central Gaza after sundown Sunday, chanting, "No to Moussa Arafat, yes to reform."

Many Palestinians feel Moussa Arafat is a member of the "old guard," steeped in corruption and known as a cruel commander.

It was the most serious internal unrest since the anti-corruption protests of 2003 that forced Arafat to appoint a new government with the first Palestinian prime minister, Mahmoud Abbas. He resigned after only four months.

There also was no solution to the standoff between Arafat and his current prime minister, Ahmed Qureia, who submitted his resignation in frustration over his inability to effect change.

"I totally reject your resignation and consider it nonexistent," Arafat told Qureia on Sunday.

Up to now the head of the Palestinian intelligence services, Moussa Arafat has a reputation for ruthlessness. He was among the founders of Fatah in 1965 and has stood by his cousin's side since then.

In 1996, during a mass roundup of Hamas and Islamic Jihad militants, Moussa Arafat shaved the heads and beards of the men he imprisoned to humiliate them. Human rights groups accused him of torture.