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Lebanon has detained a man over the killing of 10 people including his wife, two brothers and two Syrian children, a judicial source said on Thursday, in a crime that shocked the country.

The case has stirred public opinion since the discovery on Tuesday of the first nine bodies near the village of Baakline in the Chouf area southeast of Beirut, in what Prime Minister Hassan Diab described as an "appalling crime."

"Police found the perpetrator at 2:00am hiding in the garden of a home in the area of Ainbal near Baakline and detained him," the judicial source said.

"He admitted that he suspected his wife was cheating on him with his brother, so he decided to stab her to death in the marital home," the source added.

The wife's family has denied accusations against her, in a statement published by local media.

The man then invited his brother to join him on a hunting trip to the Baakline river, the judicial source said, where he killed him with a hunting rifle.

His body was the 10th to be discovered.

In a subsequent rampage, the man killed anyone in his path, including six Syrians - including a man and his two boys - and another brother, the source said.

Local media said another Lebanese man was also killed.

On social media on Thursday, the hashtag #Baakline was trending, with users condemning the mass killings.

"Down with disgusting male excuses. He is a criminal and a killer," women's rights activist Hayat Mirshad wrote on Twitter.

The grisly events come as Lebanon is under lockdown to stem the spread of the novel coronavirus, and grappling with its worst economic crisis since the 1975-1990 war.

Agencies