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More Syrian troops left Lebanon (search) ahead of a U.N. envoy's crucial visit to extract a timetable for a total withdrawal, as Lebanon's political landscape got bleaker Thursday, with the opposition accusing Damascus (search) of seeking to delay elections to keep a loyal legislature in place.

Syria (search) apparently wants to ensure that it continues to wield influence in Lebanon despite accelerating the pace of its troop withdrawals from a country it has controlled for nearly three decades. The opposition experom the anti-Syrian opposition, lawmaker Ghattas Khoury called on pro-Syrian caretaker Prime Minister Omar Karami to step down as he promised and allow President Emile Lahoud to appoint someone else to try to form a new Cabinet.

"The Lebanese-Syrian security authority ... is working to scuttle the parliamentary elections in a serious attempt to extend the current legislature's mandate in an illegitimate and unconstitutional manner," charged Khoury, reading from a statement written after nearly three hours of discussion.

Syria, which is withdrawing its army from Lebanon under international pressure, insists it does not interfere in Lebanese politics.

More Syrian troops left Lebanon overnight as the pace of the withdrawal picked up. A convoy of 30 Syrian trucks, loaded with equipment and ammunition, left the village of Kfar Kouk in the southern part of the Bekaa Valley on Wednesday night for the Syrian border, Lebanese security officials said.

A second convoy -- of 14 vehicles -- headed out from the eastern town of Anjar, where Syrian military intelligence has its Lebanese headquarters, witnesses said, speaking on condition of anonymity. However, Syrian military intelligence units remained in the town.

U.N. envoy Terje Roed-Larsen is expected to visit Lebanon and Syria later this week to discuss the implementation of a 2004 U.N. Security Council resolution demanding a complete Syrian withdrawal and an end to Syrian influence in Lebanese politics. Roed-Larsen leaves for the region Thursday.

Syrian President Bashar Assad has said he will be able to provide "the concrete date" for Syria's complete withdrawal by the time of the visit.

In the past weeks, Syria has removed 6,000 of its 14,000 troops in Lebanon.

But the opposition, while demanding a complete troop withdrawal, says Syria is trying to maintain its hold through the political machinations in Beirut.

Khoury accused Karami, who has failed to form a government since March 10, of "stalling" in his resignation to defer holding elections. The staggered elections are due to be held in late April and early May, and the parliament's term ends May 31.

Karami "has been designated to hinder the formation of a Cabinet, rather than forming one," said Khoury, sitting behind a big portrait of former Prime Minister Rafik Hariri, whose Feb. 14 assassination was the spark that threw Lebanon into political turmoil.

Karami, a staunch ally of Syria, had said he would bow out of trying to form a Cabinet. But on Wednesday, he seemed to waver, saying he would consult his political allies before making a final decision. Newspapers reported Thursday that this consultation would take place Friday.

Elections cannot be called until a government is formed to steer a new electoral law through parliament. If they're not held by May 31, the opposition fears the pro-Syrian majority in parliament will extend the current legislature's life for months.

The opposition met Thursday at the family home of Hariri whose assassination provoked massive anti-Syrian demonstrations that forced the government to resign and accelerated the withdrawal of Syrian troops from Lebanon.