CAIRO, Egypt — The capture of Saddam Hussein's feared half-brother may mean that Syria, long blamed for Middle East mayhem, is bowing to U.S.-led international pressure to shed its image as a sponsor of regional instability.

Syria, accused of assassinating a former Lebanese prime minister, aiding anti-Israeli extremists and fanning the insurgency in Iraq, handed over Sabawi Ibrahim al-Hassan to the Iraqi government as an apparent goodwill gesture to ease tensions with the United States, Iraqi government officials said yesterday on condition of anonymity.

The Bush administration has demanded that Syria stop aiding Mideast militants and withdraw its 15,000 soldiers from neighboring Lebanon.

The handover of al-Hassan, who was No. 36, or the 6 of diamonds, on the "deck" of 55 most-wanted Iraqis compiled by U.S. authorities after the ouster of Saddam in April 2003, follows two recent deadly bombings in the Middle East that have escalated regional tensions and led some to point to possible Syrian involvement.

The Feb. 14 bomb that killed former Lebanese Prime Minister Rafik Hariri and 16 others in Beirut set off huge protests by Lebanese who blamed Syria and Lebanon's pro-Damascus government for the attack.

Responsibility for Friday's suicide bombing of a Tel Aviv nightclub that killed four Israelis was claimed by Islamic Jihad, a Palestinian militant group that has some officials based in Syria.

Syria has denied involvement in the Hariri and Tel Aviv bombings, but al-Hassan's handover and apparent improvements in Syrian safeguards on its long, porous border with Iraq, as well as promises to gradually withdraw troops from Lebanon, indicate that Syrian President Bashar Assad is showing signs of complying with increasing demands to support U.S.-backed efforts to stabilize the volatile Middle East.

The U.S. State Department, which withdrew its ambassador to Syria after Hariri's assassination, had no immediate reaction, although spokesman Steve Pike said there was no change in the status of Ambassador Margaret Scobey.

The French ambassador to the United States, Jean-David Levitte, told CNN's "Late Edition with Wolf Blitzer" that al-Hassan's handover "would be certainly a positive development, and that's exactly what we expect from Syria."

Iraqi officials say al-Hassan and 29 other members of Saddam's former Baathist regime were rounded up in the northeastern Syrian town of Hasakah and handed over at the nearby Iraqi border to authorities there.

Capt. Ahmed Ismael, an Iraqi intelligence officer, said al-Hassan was handed to the Iraqis yesterday. Another Iraqi official said Syrian security forces expelled al-Hassan after he and his supporters had been turned back in an earlier attempt to cross the Syrian border into Lebanon and Jordan.

Officials in interim Prime Minister Ayad Allawi's office confirmed al-Hassan's capture but gave no other details. Syria did not say when he was captured but indicated it was in the past two weeks.

The capture is an important one, as al-Hassan is widely believed to have been a leading figure in financing and orchestrating the ongoing anti-U.S. insurgency in Iraq. The United States had offered $1 million for his capture.

Al-Hassan, who shared a mother with Saddam, was the latest in a series of arrests of important insurgent figures that the Iraqi government hopes will deal a crushing blow to violent opposition forces.

A week ago, authorities grabbed a key associate and the driver of Jordanian-born insurgency leader Abu Musab al-Zarqawi, leader of al-Qaida in Iraq and believed to be the mastermind behind the ongoing bombings, beheadings and attacks on Iraqi and American forces.

Saturday's Baghdad newspaper Al-Mada reported that Syria also provided information that led Iraqi authorities to breaking up 35 insurgent cells in the northern Iraqi city of Mosul and arresting some 750 suspected militants.

A major general in charge of intelligence at the Iraqi Interior Ministry linked al-Hassan's arrest to the high-profile arrests in Mosul.

"We captured him after we captured those terrorists in Mosul which he had connections with," said Maj. Gen. Hussein Kamal, who declined to provide details.

The Syrians have a record of complying under pressure.

Under threats of invasion from Turkey, Syria expelled Turkish Kurdish guerrilla leader Abdullah Ocalan in October 1998 after he had operated from Damascus for years.

In 2000, Syria handed over Egypt's most-wanted terrorist, Rifaa Taha.

Taha led the notorious al-Gamaa al-Islamiyya, which was responsible for a decadelong bloody rebellion to overthrow the secular government of Egyptian President Hosni Mubarak. In return, Mubarak persuaded then Israeli Prime Minister Ehud Barak to resume peace talks with Syria, but the talks collapsed that year.

In recent years, U.S. officials have praised the assistance they have received from Syria in tracking and nabbing members of Osama bin Laden's al-Qaida terrorist network.

Under Saddam, al-Hassan led the dreaded General Security Directorate, which was responsible for internal security, especially cracking down on political factions that opposed the Iraqi leader. Al-Hassan was accused of the widespread torture of political opponents.

The government statement on his capture said al-Hassan had "killed and tortured Iraqi people" and "participated effectively in planning, supervising and carrying out many terrorist acts in Iraq."

Al-Hassan also was thought to have been responsible for setting up shadowy companies in neighboring Jordan to overcome U.N. sanctions imposed after Iraq invaded neighboring Kuwait, prompting the first Gulf War in 1991. Internationally, al-Hassan's name was linked to attempts to sell looted Kuwaiti treasure.

However, al -Hassan was among the family members marginalized by Saddam in late 1995 and early 1996 in the wake of a botched coup attempt and the defection of two cousins to Jordan. He was given a post as a presidential adviser, the last position he held in Saddam's government.

"This is a great achievement for the Iraqi security forces," national-security adviser Mouwafak al-Rubaie told Dubai's al-Arabiya TV. "It is also a lesson for others to give themselves up to the Iraqi authorities."

Saddam's two other half-brothers, Barzan and Watban, were captured in April 2003 and are expected to stand trial with Saddam at the Iraqi Special Tribunal.

Both appeared before the special court in Baghdad along with Saddam and other captured regime during preliminary hearings to hear the charges against them.

Iraq's post-election Shiite Muslim power broker, United Iraqi Alliance leader Abdel Aziz al-Hakim, said al-Hassan's arrest signaled troubled times for the insurgency.

"Those criminals are on the run and we will chase the rest of them," he said. "We will work on arresting all the criminals, either those inside Iraq or those in other neighboring countries, so that they can stand fair trial and be punished for the crimes they have committed against the Iraqi people."

Material from Knight Ridder Newspapers is included in this report.