Investigators said Saturday Police are now focusing on the terrorist group Jemaah Islamiyah (JI) responsible for Friday's bombing attacks.

The bombers struck the JW Marriott and Ritz-Carlton, luxury hotels popular with businessmen and diplomats and considered to be among the most secure buildings in the capital.

Police said at a news conference on Saturday that nine people were killed and 53 wounded in the blasts.

Investigators noted that only JI has the skills and connections necessary to put into action bomb attacks in heavily supervised places such as the two hotels hit on Friday.

It has the signature of our 'friends', said a retired Southeast Asian police officer now focused on counterterrorism in the region.

The casualties included citizens of Indonesia, the United States, Australia, South Korea, the Netherlands, Italy, Britain, Canada, Norway, Japan and India.

The blasts are a severe blow for President Susilo Bambang Yudhoyono, who was re-elected earlier this month in a landslide victory on the back of strong growth in Southeast Asia's biggest economy.