Iraqi security forces have arrested a nephew of Saddam Hussein, described as the top financier of the Sunni-dominated insurgency, after Syrian authorities forced him to return to his native country and told American officials where he was hiding in Baghdad. Yasir Sabhawi Ibrahim, son of Saddam's half brother Sabhawi Ibrahim Hasan al-Tikriti, was arrested in a Baghdad apartment, several days after Syrian authorities forced him to return to Iraq, security officials told The Associated Press in a telephone interview from Cairo. They spoke on condition of anonymity because they weren't authorized to deal with the media. They did not say exactly when the arrest was made. Syria handed over Yasir Sabhawi Ibrahim's father, No. 36 on the US list of 55 most-wanted Iraqis, along with 29 other former Ba'ath Party officials in late February, after months of denying Iraqi accusations that Damascus was harboring fugitives. That was seen as a goodwill gesture by Syria. The latest Syrian action came as relations with the United States continue to deteriorate, however, with Washington insisting Damascus could do more to block the flow of foreign fighters into Iraq. Also, the Syrians appear increasingly concerned they will be named complicit in a UN investigation of the assassination of former Lebanese Prime Minister Rafik Hariri. A report of the UN probe was to be given to Secretary-General Kofi Annan on Thursday. Damascus denies actively supporting insurgents battling US and Iraqi forces but says it is virtually impossible to lock down its porous desert frontier with Iraq. Syrian President Bashar Assad says his country was not involved in Hariri's killing. An Iraqi security official, who serves as a coordinator between Iraqi authorities and US military intelligence, described Yasir Sabhawi Ibrahim as the most dangerous man in the urgency. A second official, who is a senior member of the Iraqi Defense Ministry, said the arrest would be a serious blow to terrorist networks. Both officials said Syrian authorities "pushed" Ibrahim into Iraq but did not hand him over. The Syrians knew where he was hiding in Baghdad and told US authorities. They gave the information to Iraq security forces that carried out a "fast, easy" raid on the fugitive's apartment, the Defense Ministry official said. The Iraqi officials believe the suspect was controlling Ba'ath Party funds in Syria, Jordan and Yemen and had been running a vast network of insurgents inside Iraq. They also claim he was acting as coordinator between Ba'athist insurgents and al-Qaida in Iraq, the terror network of Jordanian-born militant Abu Musab al-Zarqawi. Yasir Sabhawi Ibrahim was believed to be second in command of the Iraqi-led insurgency behind Younis al-Ahmad, a former member of the Ba'ath Party leadership believed to be still in Syria. Officials in Syria were not available for comment on the arrest. On July 21, the US Treasury Department froze the US assets of the suspect as well as the five other sons of al-Tikriti. On Sept. 19, Iraq's Central Criminal Court sentenced another of al-Tikriti's sons, Ayman, to life in prison on charges he helped fund the insurgency and was a bomb-maker. It was the first known trial of any of the former leader's family members.