Israel is carefully watching developments in Lebanon where the government collapsed after Hezbollah ministers walked out, a senior government official said on Thursday.

The crisis erupted on Wednesday after the Shia party and its allies resigned from cabinet in protest over a UN probe into the 2005 assassination of former premier Rafiq Al-Hariri.

"This crisis is an internal Lebanese issue. But we are following everything that is happening with vigilance," the official said, stressing Israel was "clearly opposed to any escalation" in the situation along the northern border.

His comments echoed remarks by Israeli Defence Minister Ehud Barak on Wednesday as news of the crisis emerged.

"Israel is vigilantly following the situation in Lebanon," Barak was quoted as saying by a ministry spokesman.

Most Israeli commentators said Thursday they were confident Hezbollah would refrain from using the crisis as an excuse to start a confrontation with Israel.

Israel led a devastating war against Hezbollah in the summer of 2006 which killed more than 1,200 people in Lebanon, mainly civilians, and 160 Israelis, mainly soldiers.