About 500 trucks have been stranded at border checkpoints, costing Lebanon $1.5 million in lost trade, the head of the Lebanese Farmers' Association, Ibrahim Tarshishi said.
Waddah Fakri, head of the Southern Farmers' Association, told the newspaper, Daily Star: "The situation is extremely dangerous, because Lebanon exports all of its products through Syria to other Arab countries, especially to the Gulf region."
The tightening of security drills in the past few days has virtually halted all truck movement into Syria, the latest sign of growing tension between the two neighbours since Damascus ended its 29-year military presence in Lebanon in April.
Syria, which withdrew its troops from its tiny neighbour under Lebanese and international pressure, said the inspections were needed to prevent weapons from entering the country.
Outgoing Lebanese Prime Minister Najib Mikati said he had a telephone conversation on Monday with Syrian Prime Minister Naji al-Otari and the Syrians had promised to ease traffic at the border soon.
"I discussed with him ways to resolve the problem and, in fact, things are taking a positive turn towards easing the passage of trucks and alleviating security measures," Mikati told reporters.
Elections that ended on 19 June returned an anti-Syrian majority to parliament for the first time since Lebanon's 1975-1990 civil war.
Anti-Syrian Prime Minister-designate Fouad Siniora is set to announce a new government shortly.