In a separate incident, seven injured Syrians were treated by Israeli soldiers before being transferred to a hospital in northern Israel.
"About two days ago, two trucks loaded with dozens of tons of explosives crossed the Masnaa Lebanese-Syrian border crossing, and this has been happening since May 2012," the Lebanese National News Agency quoted Member of Parliament Khaled Daher as saying during a news conference Saturday.
"The problem is that it is happening with the knowledge of the Lebanese armed forces and the army intelligence, as if it were a simple matter," he said.
Documents were submitted by opposition members in Parliament, backing his claims, the news agency said.
Daher called on Lebanese Prime Minister Najib Miqati to step down.
His comments came as the United Nations High Commissioner for Refugees revealed at least 283,000 refugees have fled Syria to Lebanon since the outbreak of violence two years ago.
In a separate incident Saturday, seven injured Syrian nationals were treated by Israeli soldiers before they were transferred to a hospital in northern Israel. It was unclear whether they were members of the rebel forces fighting Syrian regime forces or civilians. The seven made their way to the border area in the northern Golan Heights where they were spotted by the soldiers, the army said.
Dr. Oscar Ambon, director of the Ziv Medical Center, said one Syrian was in critical condition and four others were in moderate condition, Ynetnews.com reported. He said the seven are expected to remain hospitalized for a week. The website said the seven will then be returned to Syria.
An Israeli military source told the website the incident was "isolated" and does not reflect a change in Israel's policy against any breaches of the border fence "with the exception of special humanitarian cases."