They said the Katyusha rockets were fired at around 7pm (1700 GMT) on Monday and that police were trying to find out who had fired them.

Initial indications were that Hizb Allah, the main group fighting Israel from Lebanon, was not involved.

An Israeli army spokesman did not immediately comment on the rocket launch, saying only than an explosion was heard near Israel's border town of Shlomi.

"We are investigating," he said.

Tense border

One Lebanese security source said the rockets were fired from north of Naqura, a Lebanese town close to the border.

One rocket landed near Shlomi, while the other fell into the sea on the Lebanese side of the border.

Israel withdrew from southern Lebanon in 2000 after a 22-year occupation but there have been sporadic clashes in the border area since, mostly between Hizb Allah fighters and the Israeli army.

Other groups have claimed responsibility for firing rockets towards Israel in the past. A Hizb Allah spokesman said he had no information about Monday's incident.

Earlier this month, the United Nations said it was concerned about the possibility of rising tensions along the Israeli-Lebanese frontier, and called for maximum restraint.