Syria has massed thousands of troops along its border with northern Lebanon in what officials in Beirut fear is a prelude to the first incursion since Syrian forces pulled out three years ago.

Although Damascus insists that its forces are conducting an antismuggling operation, the Lebanese Government is eyeing the moves with unease, believing that the unusual scale of the deployment has more to do with tensions between the two countries over recent sectarian clashes in northern Lebanon.

“People around here are worried. We don’t know why the Syrians have arrived like this,” said Ali, 18, a farmer in the tiny hillside hamlet of Hekr Janin overlooking the border.

Much of Lebanon’s northern border with Syria follows the Kabir, or Great river, which despite its name, is little more than a trickle after the hot summer months. Lined by trees and bamboo thickets, the river meanders through a narrow floodplain of meadows and crop fields flanked by steep hills of black basalt.

The Lebanese media report that between 8,000 and 10,000 Syrian special forces have taken up positions along some of the hills overlooking the Kabir.

Their surprise deployment comes after several months of clashes in Tripoli, northern Lebanon, pitting the majority Sunnis against the minority Alawites, an offshoot of Shia Islam.

The small Alawite community in Lebanon is a close ally of the Syrian regime. President Assad of Syria is an Alawite and most top positions in the Syrian security and military apparatus are filled by them

Much of northern Lebanon is populated by Sunnis, the majority of whom are supporters of the Future Movement, which is headed by Saad Hariri, the son and political heir of Rafik Hariri, whose 2005 assassination is widely blamed on Syria.

Last month Mr Assad said that he had warned his Lebanese counterpart, Michel Suleiman, of the “problem of extremism” — a reference to Islamic militants, who he said were responsible for destabilising northern Lebanon. He said that he had urged Mr Suleiman to dispatch Lebanese troops to confront the extremists.

Mr Assad has also likened the situation between Syria and Lebanon to that of Russia and Georgia. His comments sparked speculation in Beirut that Damascus could be contemplating a military incursion into northern Lebanon to protect the Alawite community from the Sunni militants.

Tucked into a dusty olive grove on a hill overlooking the Kabir river, more than a dozen white canvas Syrian military tents were clearly visible from Hekr Janin and the neighbouring Lebanese village of Dabbabiyeh.

Two miles to the east, in a large field beside a small village, another encampment could be seen, with more trucks parked in a neat row along with a small building festooned with antennas. “None of them were here two weeks ago,” said Khaled, a shepherd, who used to take his flock of 300 sheep to graze on the lush green grass growing beside the river.

Now, Khaled said, it had become too dangerous to approach the river. Four days ago he said Syrian soldiers had opened fire at him from the other side of the border when he was cutting wood near the river. “I could feel the wind of the bullets passing by,” he said. “They are shooting at anyone going close to the river.”

Some Lebanese military sources say that Syrian troop numbers have been exaggerated by the press, and that Damascus has informed the Lebanese Government that the manoeuvres are part of a renewed attempt to crack down on cross-border smuggling.

“The numbers are much less than is being reported. They are special forces and they are there to patrol the border and stop smuggling,” a senior Lebanese army officer said.

Smuggling has long been a popular source of income for residents of Lebanon’s impoverished border districts. Smuggling along the northern border has, however, declined since a German-led UN security operation took effect last year. That has raised questions about why Syria would deploy such large numbers of special forces to combat smuggling in an area where it has declined.

Syria has only recently broken out of its international isolation, playing host to President Sarkozy in Damascus. But its muscle-flexing gesture along the northern border of Lebanon risks undermining its recent diplomatic efforts.

“It will be seen as antagonistic. I think this move is a miscalculation that can only do them harm,” said a European diplomat in Beirut.

Clash of faith

Alawites are a small offshoot of Shia Islam, which broke away from Sunni Islam after the death of Muhammad. Their doctrine deifies Ali, the son-in-law of Muhammad. They interpret the pillars of Islam as symbols; some celebrate many Christian festivals

The Baathist Government in Syria is dominated by Alawites. They comprise about 12 per cent of Syria’s population

Their numbers are small in Lebanon but they became influential during Syria’s military presence

Longstanding political conflict between the government coalition and its opponents, led by the Alawite-linked Hezbollah, was largely resolved in May, but divisions remain

Since late June dozens of people have been killed in the predominantly Sunni city of Tripoli in sectarian fighting between Sunni and Alawite gunmen

The violence has been linked to lingering disputes between the anti-Syrian majority coalition and the Opposition

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