Lebanon is accusing Israel of waging a high-tech propaganda campaign against its citizens using anti-Hezbollah recorded phone calls and mass text messages.

The allegations of interference with Lebanon’s telecommunications network, first reported by press outlets affiliated with Hezbollah, were given official weight during the weekend in an official letter from the Lebanese foreign minister, Fawzi Salloukh, to U.N. Secretary-General Ban.

A Jerusalem source familiar with Israel’s methods in southern Lebanon dismissed some of the details in Mr. Salloukh’s letter as “highly doubtful.”

The finger-pointing comes days after an exchange of bodies and prisoners between Israel and Hezbollah, and as the Shiite organization is increasing its hold over Lebanese politics and strengthening its relations with its patron Syria.

Yesterday, during the first visit to Beirut by a high-level Syrian official in three years, Foreign Minister Walid al-Moallem handed a letter to President Suleiman of Lebanon, inviting him to a meeting in the Syrian capital with President al-Assad.

Syria occupied Lebanon between 1976 and 2005, and according to its ruling Baath Party doctrine, Lebanon is a Syrian province. The Assad family has long refused to recognize Lebanon’s sovereignty, let alone establish diplomatic relations, as the U.N. Security Council has called for in several resolutions.

The reported agreement to begin negotiations over the establishment of such relations could lead to a delineation of borders between the two countries, another council demand that Syria has rejected.

Syria considers Lebanon’s new president, Mr. Suleiman, a friendly figure. A former Lebanese army chief, his election was made possible by a Qatar-backed deal to end a months-long standoff that arose from government efforts to dismantle a Hezbollah telecommunications system in areas under the group’s control. As part of the deal, Prime Minister Siniora agreed to allow Hezbollah ministers to enter his government and gave them veto power over any policy decision.

Since July 16, when Israel received the bodies of two of its soldiers and Hezbollah secured the release of a convicted murderer, Samir Kuntar, and other prisoners held in Israel, Lebanon has been “subjected to a large scale interference in its communication network originating from Israel,” Mr. Salloukh wrote to Mr. Ban.

“Threatening phone calls and instant messages” warn against cooperating with Hezbollah, he added.

Such a campaign is an “unacceptable infringement” and a violation of Security Council resolutions, Mr. Salloukh wrote. “The messages always ended with ‘state of Israel,'” he wrote.

Press outlets in the region have reported that since the 2006 war between Israel and Hezbollah, Israel has used bulk text messages and robo-calls to turn the Lebanese against the Shiite group, which it considers a terrorist organization.

“It is highly doubtful that we would admit to it by ending such calls with a ‘state of Israel’ artist signature,” an official in Jerusalem familiar with such tactics said. The official, who requested anonymity, called the letter’s veracity “suspect at best.”