Clash over Israel-Lebanese border

Israeli troops regularly patrol the border area

Israeli and Lebanese forces have exchanged fire across the international border between the two countries.

Israeli officials said their troops came under fire as they searched a border area following the discovery of four explosives on Monday.

Israeli troops returned fire but no casualties were reported, security sources said.

Israel and Lebanon's Hezbollah militia fought a 34-day war last year sparked by flare-ups on the tense border.

Since that conflict the international border between Israel and Lebanon has been policed by a combination of Lebanese government soldiers and UN troops.

Israel said the bombs discovered earlier in the week were recently planted by Hezbollah, in violation of the terms of the ongoing ceasefire.

Hezbollah has denied the charge, saying the bombs had been there since last summer's fighting.

The BBC's Simon Wilson, in Jerusalem, says the flare-up is serious, but not as serious as if the exchange of fire had involved Israel and Hezbollah fighters.