BAGHDAD: A restaurant boat moored on the banks of Baghdad's Tigris River hosting a private party sank on Thursday night with at least 80 people on board, leaving five people dead, Iraqi officials said.

"A boat belonging to the Lebanese Club in the Karrada area sank tonight while there were 80 people on board," an interior ministry official said, adding that the cause was not immediately clear.

Baghdad provincial council member Mohammed Jassem al-Rubaie told AFP at the club, where the boat was moored, that 150 people had been on board and that five people died.

"Most of them were Iraqis; only a few were guests from Middle Eastern countries," he said, adding that the party was for US heavy equipment manufacturer Caterpillar.

"I am 100 percent sure that it was just an accident," he said.

A crowd of people, including relatives of those on the boat, gathered at the club following the sinking.

Some stood next to an ambulance crying, while others shouted that the owners of the club should be held responsible for the deaths.

Fire trucks and a number of police were also at the scene.