The Japanese government pledged on Monday to offer support to Indonesia, which has been hit by a devastating tsunami as the death toll climbed to 373.

Japanese Foreign Minister Taro Kono, in a message sent to his Indonesian counterpart Retno Marsudi, expressed condolences to the victims' families and hoped for quick recovery of the disaster-hit areas.

"The Japanese government is ready to provide utmost support to Indonesia," Kono said.

The Indonesian disaster agency on Monday put the death toll of the catastrophe at 373 with 1,459 others injured, after the tsunami occurred two days ago along the coast of Sunda Strait between Java and Sumatra islands.

As rescue operations for victims of the tsunami, caused by an underwater landslide after a volcanic eruption, were underway, rescuers believed many victims remained trapped under the debris swept by sea waves, said Sutopo Purwo Nugroho, spokesman of the National Disaster Management Agency.

The tsunami has destroyed 611 houses, 69 hotels and villas, 420 ships and boats along the coast, Sutopo said.