A 41-year-old Melbourne man is among 42 people killed in Lebanon in five days of deadly violence between government and opposition supporters.

Fadi Sheikh, from Craigieburn, was one of 12 people killed when 100 pro-government loyalists attacked the office of an opposition political party in the country's north, ABC Radio reports.

Australian Lebanese Youth Association spokesman Antoun Issa told the ABC Mr Sheikh, who is married, with four children, was in the region visiting his parents when he was killed.

He had been in a coalition office used for providing the community with safety advice in the city of Halba in northern Lebanon, close to the border with Syria, when it was stormed by a pro-government mob.

'Hunted down and killed'

"He just happened to be there in the wrong place at the wrong time when a mob of about 100 pro-government loyalists attacked," Mr Issa said.

"It was quite brutal. Some people tried to escape and were hunted down and killed."

Mr Issa, a family acquaintance, said Mr Sheikh had been due to return to Australia in two weeks' time.

He said Mr Sheikh's wife was "absolutely hysterical, she can't even speak... she's mortified".

A spokesman for the Department of Foreign Affairs and Trade in Canberra said the death underlined the highly dangerous situation in Lebanon, and the need for Australians to exercise extreme caution there.

'Highly dangerous situation'

DFAT said it was seeking to provide consular assistance to the man's family in Melbourne, while the Australian Embassy in Beirut is liaising with local authorities regarding his death.

Fighting between supporters of the Western-backed ruling coalition and the Hezbollah-led opposition erupted in Beirut on Wednesday, and spread swiftly around the country.

"From the day the unrest started, 42 people have been killed and 164 wounded across the country," a security official told news agency AFP.

The official said the toll could rise as a result of clashes in Druze areas southeast of Beirut late on Sunday.