Lashkar-e-Taiba (LeT) ringleaders had ambitions well beyond Mumbai and had placed India's financial hub in a list of 320 worldwide locations as potential targets for commando-style terror strikes, the Guardian has said in a report published on Thursday.
According to the report, western intelligence agencies that accessed the computer and email account of the LeT's communications chief Zarar Shah found a list of possible targets, only 20 of which were in India.
Two of the November 2008 attack's key planners - Shah and Lashkar's operations chief Zakiur Rehman Lakhvi - are now in police custody in Pakistan.
Analysts say the computer list is more of a statement of intent because Lashkar would need time to set up terrorist cells in so many places.
Islamabad's decision to bring criminal charges against nine men accused of involvement in the Mumbai attack has partly placated Indian officials but officials in New Delhi have been warning that they want to see people brought to justice for terrorist acts.
"There has been some speculation that raids in Spain which netted 12 men - an Indian and 11 Pakistanis - were a result of the investigations into Lashkar's role in the Mumbai attacks," the report said.
"The dozen men were reportedly picked up for forging passports and other travel documents for terror organisations, including Al -Qaeda. Pakistan's government has said the Mumbai attacks were partly planned from Spain."
The US has been trying behind the scenes to coordinate intelligence exchanges between the two nuclear-armed rivals. The CIA has worked hard to be seen to help New Delhi - including by recovering phone numbers deleted by the terrorists on their satellite phones.
The fallout from Mumbai has destabilised the government of Pakistan's President Asif Ali Zardari, which is attempting to face down Islamist groups his predecessors cultivated.
Intelligence agencies have warned that Mumbai raises the spectre of a new style of terrorist assault. The city of 19 million people was brought to a halt by 10 heavily armed gunmen rampaging through a railway station, a house, restaurants and hotels for three days, killing over 170 people.