MANILA - The United States on Saturday condoled with the Philippines after a bomb attack in the southern city of Davao, which was claimed by Abu Sayyaf extremists, left scores dead and wounded.

Washington also offered to help investigate the incident, which caused President Rodrigo Duterte to place the entire country under a "state of lawlessness."

"The United States offers deep condolences to the families and other loved ones of the victims of the explosion in the Philippines’ Davao City, and our thoughts and prayers are with the injured," US National Security Council spokesperson Ned Price said in a statement.

"We understand that local authorities continue to investigate the cause of the explosion in the night market, and the United States stands ready to provide assistance to the investigation," he added.

US President Barack Obama will have an opportunity to personally offer his condolences to Duterte when the two leaders meet on the sidelines of the ASEAN Summit in Laos next week, Price said.

A spokesman for the Abu Sayyaf said the bombing was a show of unity with Islamic State jihadists. The group also warned of more attacks.

The Abu Sayyaf, known internationally for kidnap for ransom sprees that target foreigners, recently pledged allegiance to IS.