"Al Qaeda set the blueprint for terrorist operations and now we see different people, different groups in different parts of the world, copying it," said George Kassimeris, an expert in conflict and terrorism.

He said the "underlying theme is to cause as much havoc as possible and this is exactly what has happened in India".

Kassimeris, a senior research fellow at the University of Wolverhampton, said the Islamic extremist group created the "modus operandi" of attacking vulnerable civilian targets with no warning, long-term plans or demands.

Witness accounts that gunmen were looking for US and British nationals suggest they want to grab international attention, he added.

"There is no specific operational or logistical plan, they just want to inflict as much damage and injury as possible," he was quoted as saying by the Daily Telegraph.

"The fact they have gone for western targets confirms initial fears these people are out to inflict as much damage as possible," he told the British daily.

Kassimeris said those responsible were likely to be Islamic religious extremists.