BERLIN - A U.N. investigator has named a brother-in-law of Syrian President Bashar al-Assad as a suspect in the killing of former Lebanese Prime Minister Rafik al-Hariri, a German report said on Tuesday.

Stern magazine, in extracts from an article due to appear on Thursday, named Syrian military intelligence chief Asef Shawkat, as a suspect in the probe led by chief United Nations investigator Detlev Mehlis.

Shawkat, who is Assad's brother-in-law, is widely seen as the second most powerful man in Syria after Assad.

Mehlis, a German prosecutor, had questioned Shawkat "not as a witness, but as a suspected person", said Stern, without giving the source of its information.

Mehlis is due to present his report to U.N. Secretary-General Kofi Annan on Friday on the Feb. 14 killings of Hariri and 20 others in a truck bomb blast in Beirut.

Diplomats and Lebanese political sources say they expect Mehlis to name some Syrian officials in his report. But for him to point the finger at a member of Assad's inner circle would be political dynamite.

Assad had appointed Shawkat as military intelligence chief last February. The announcement was made by Syrian officials four days after Hariri's assassination.

The Syrian president said in a CNN interview last week that Syria was not involved in Hariri's death and that he could never have ordered it.

However, if the United Nations concluded Syrians were involved, they would be "traitors" who would face an international court or the Syrian judicial process, he added.

Blaming Syrian officials for the killing would likely intensify U.S. pressure against Damascus and could prompt U.N. Security Council action.

Stern said that of 10 high-ranking Syrian diplomats and secret service officials questioned by Mehlis, five were considered as suspects in the assassination. They included Rustum Ghazaleh, former Syrian intelligence chief in Lebanon.

Four pro-Syrian Lebanese generals have also been detained since August on Mehlis' recommendation and charged with murder, attempted murder and carrying out a terrorist act. (Reuters)