BEIRUT (Reuters) – A United Nations investigator intends to question Syrian officials directly as part of a probe into the killing six months ago of Lebanese former prime minister Rafik al-Hariri, a U.N. official said on Saturday. Detlev Mehlis will also probably ask for more time than the designated three months to complete his findings, the official said. “Detlev Mehlis needs to directly interview Syrian officials concerned. He needs to visit Syria for this purpose,” U.N. spokesman Najib Friji told Reuters. “The Syrians have agreed in principle to cooperate with Mehlis but he has yet to receive an official Syrian response to visit the country.” Mehlis, a veteran German prosecutor, is leading a 50-member team investigating the February 14 bombing that killed Hariri and 20 others in Beirut, throwing Lebanon into its worst crisis since the end of the 1975-1990 civil war. Many Lebanese hold Syria, which controlled Lebanese politics and security in the 15 years following the end of the civil war, at least indirectly responsible for Hariri’s killing. Damascus denies any role but withdrew its troops from Lebanon in April, ending a 29-year military presence amid mass anti-Syrian street protests and intense international pressure. The U.N. Security Council ordered the investigation, which began in mid-June, after a U.N. fact-finding mission found Lebanon’s own inquiry to be “seriously flawed.”