BEIRUT (Reuters) - Lebanons parliament on Thursday elected Nabih Berri as speaker for the coming four years, extending his 17-year leadership of the chamber in a vote that underlined improved ties between rival politicians. Berri, an ally of the military and political movement Hezbollah, stood uncontested for the post, reserved for a Shia Muslim according to a sectarian power-sharing system. Ninety of parliaments 128 members voted for the 71-year old, including the Future Movement of Sunni politician Saad al-Hariri, one of Berris main opponents during a crisis that pushed Lebanon to the brink of civil war last year. Hariris March 14 coalition won a parliamentary majority in a June 7 election, defeating a rival alliance including Berris Amal movement and Hezbollah, which between them dominate Shia representation in Lebanon. Hariri, 39, is a frontrunner to head the new government. His decision to back Berri is seen as supportive of Lebanons stability and a further sign of improved ties between Syria and Saudi Arabia, whose rivalry was viewed as a major cause of the countrys crises in recent years. Saudi Arabia and western countries including the United States have been major supporters of Hariri and his allies in their power struggle with rivals backed by Syria and Iran. Addressing parliament after his election, Berri called on Lebanons politicians to seize the regional and international moment ... to strengthen Lebanons peace and stability. This requires us to facilitate the establishment of a national government, said Berri, viewed as one of Syrias closest allies in Lebanon. Speaking after a meeting with Berri on Wednesday, Hariri said voting for the Amal leader was a decision that would strengthen national unity and preserve civil peace. President Michel Suleiman will hold consultations with parliamentarians on Friday and Saturday to decide on the next prime minister. On Saturday he will designate the candidate with most support. Many of Hariris allies in the majority coalition have already stated their support for his candidacy. Hezbollah had called for the formation of a national unity government with veto power for the minority alliance after the parliamentary election, though the group has not repeated the demand since the vote.