"Mumbai is coming to London," said a senior detective from SO15, the Metropolitan police's counter-terrorism command.
He warned that the big business houses having their base in major locations of the city may be targeted in a shooting.
According to The Times reports, the warning has underlined an assessment that a terrorist cell may be preparing an attack on London early next year.
The warning, probably the bluntest issued by police, has underlined an assessment that a terrorist cell may be preparing an attack on London early next year, the report said.
During the Mumbai attacks in Nov in 2009, 10 terrorists from Pakistan had killed 166 people over three days in India's financial hub.
"Before, there has been speculation. Now we are getting what appears to be a definite plot to carry out a firearms attack on London," the official said.