Secretary-General Ban Ki-moon expressed concern that UN efforts have so far failed to get Lebanon to approve an international tribunal to prosecute suspects in the assassination of former Prime Minister Rafik Hariri. He urged the Lebanese parliament to act before its term ends next month. In an interview Thursday with the Associated Press, Ban said UN legal chief Nicolas Michel's recent visit to Lebanon and his talks with all the key parties, including Parliament speaker Nabih Berri, had not produced "any positive development." "That is why I'm concerned," he said. "The international community expects that there should be no impunity. Any perpetrators of this crime should be brought to justice." Hariri, who was seen as an opponent of Syrian influence in his country, and 22 others were killed by a bomb in Beirut on Feb. 14, 2005. The assassination provoked such an outcry in Lebanon and around the world that Damascus was forced to withdraw its troops from Lebanon, ending a 29-year presence. The United Nations has approved an international tribunal to prosecute suspects, but Berri, who is pro-Syrian, has refused to convene parliament so the Lebanese government can ratify it. In light of Berri's refusal, anti-Syrian Prime Minister Fuad Saniora and 70 of parliament's 128 members have urged the UN Security Council to establish the tribunal. But Ban said he was not prepared to recommend council action now, and he refused to say how long he would wait. "The most desirable path at this time is for the Lebanese government to take constitutional procedures on the basis of national consensus," he said. "I will continue to urge this process should be taken." "As for the timing, I'm not in a position to set any deadline or timing. But what I'm concerned is the parliamentary session is going to end by the end of May. I hope (the) Lebanese government will be able to complete the constitutional procedure before this parliamentary session ends," the secretary-general said. Ban discussed the tribunal at a meeting this week in Damascus with Syrian President Bashar Assad. Last month, he visited Lebanon. An initial UN investigation into Hariri's assassination implicated the Syrian and Lebanese intelligence services. Syria denied involvement, but four pro-Syrian Lebanese generals were charged and are in custody. The secretary-general told reporters earlier Thursday that he strongly urged Assad to use his influence to promote national reconciliation in Lebanon "which will facilitate the establishment of a special tribunal." Assad replied that it is "purely" for the Lebanese people to decide on national reconciliation, Ban said. "But he will (make) his own efforts to influence the Lebanese people, to facilitate this process." Asked in the AP interview whether he had urged Assad to use his influence with Berri, Ban said he discussed parliament's ratification with the Syrian leader "in a general manner." He said Michel, the undersecretary-general for legal affairs, sought Berri's "flexibility and cooperation in this matter." The tribunal proposal has deeply divided the US-backed government and the pro-Syrian opposition in Beirut, led by the Shiite Muslim Hizbullah group. Lebanon's opposition has been demanding a national unity Cabinet in which it would have veto power over key decisions - including the tribunal. Saniora has refused to give the opposition such powers. Ban said he also urged Syria to work with Lebanon to prevent cross-border arms smuggling. Weapons transfers to Hizbullah are banned under a UN resolution that ended last summer's war between the Iranian- and Syrian-backed terrorists and Israel. Ban warned during his Lebanon visit that arms smuggling across the Syria-Lebanese border threatened the Aug. 14 cease-fire. The Security Council has authorized an independent mission to be deployed quickly to assess how the frontier is being monitored, but Syria has threatened to close the boundary with Lebanon, effectively choking the country economically, if such a mission is deployed. Ban said the Syrian government "seems to be not yet ready to receive any assessment team to their border." "I advised them it would be helpful for them and for the United Nations ... to strengthen their monitoring capacity," he said. "I will continue to discus this matter with the Syrians." Ban said "one encouraging thing" is that the Lebanese and Syrian governments have agreed to reactivate a committee that meets on border issues at a higher level.