Beirut (AFP) - The Lebanese army said Thursday it had foiled attacks planned by the Islamic State jihadist group on a tourist site and a crowded area, arresting five "terrorists".

"Military intelligence services have foiled two terrorist operations prepared by Daesh that would have targeted an important tourism site and a crowded area," the army said in a statement, using an Arabic name for IS. It was not clear when the arrests took place, but the military official said the attacks were to have been carried out "10 days ago".

They would have targeted "the Casino du Liban as well as a crowded area, like a shopping centre, the southern suburbs of Beirut or indeed the (downtown) neighbourhoods of Hamra or Ashrafiyeh", the official said.

He said "suicide bombers and armed men" were to have carried out the attacks, and added that investigations would follow on other possible cells and potential targets.

The five arrested included the alleged mastermind of the attacks, the army said.

"They admitted having previously carried out terrorist attacks against the army," it said.

Lebanon has been repeatedly shaken by attacks linked with the war in neighbouring Syria, where Lebanese Shiite militia Hezbollah is fighting in support of President Bashar al-Assad.

On Monday, five people were killed when four suicide bombers attacked a predominantly Christian village near the border with Syria.

There was no immediate claim of responsibility for Monday's attacks but they bore the hallmarks of jihadist organisations like IS or Al-Qaeda.