DAMASCUS  - Syria and U.N. investigators are discussing a date for the questioning in Austria of five Syrian officials in connection with the killing of Lebanese ex-premier Rafik al Hariri, a Syrian official said on Saturday.

"Contact with the international committee has been initiated to decide the date of the meetings with the five officials," the official said, without elaborating.

The official declined to disclose the names of the five Syrians that a United Nations team led by German prosecutor Detlev Mehlis wants to question as part of a probe into Hariri's assassination in Beirut on February 14.

A source familiar with the situation said: "From a logistical point of view it appears that it will be around Tuesday ... I am sure it will be a matter of days only before the committee meets the officials."

Syria agreed on Friday to allow U.N. investigators to question the officials at the U.N.'s offices in Vienna, after receiving guarantees from an undisclosed permanent member of the U.N. Security Council. These included a pledge that the five will be allowed to return to Damascus after being quizzed.

The Syrian move was aimed at averting a showdown with the U.N. Security Council. Sources in Lebanon had said Mehlis was close to giving up on Syrian cooperation because of demands from Damascus for a legal deal before it would permit questioning of the five officials.

A U.N. spokesman in New York said on Friday that Mehlis had informed U.N. Secretary-General Kofi Annan of the accord.

A Security Council resolution on October 31 demanded Syria cooperate fully with Mehlis or face unspecified further action.

Mehlis then summoned six top Syrian security officials -- who according to Lebanese political sources include President Bashar al-Assad's brother-in-law -- for questioning in Lebanon.

Syrian Deputy Foreign Minister Waleed al-Moualem said on Friday Damascus was aware that Mehlis wanted to interview only five Syrians, not six.

In an interim report last month, Mehlis said he had evidence of Syrian and Lebanese officials' involvement in Hariri's murder. Syria denies any role in the killing its former ally.

Lebanon has already charged four pro-Syrian security generals in connection with the assassination on Mehlis's recommendation. (Reuters)