"The security cover here is unprecedented," Pakistan's team manager Talat Ali told the News. "We have been given a good security cover since we arrived on this tour but in Kolkata it is much tighter than before. We haven't been given any reason for the additional security but we do understand that there have been threats."

Ali said Pakistan's focus would remain on drawing level in the three-Test series after they lost the first Test in Delhi. "Our safety is the responsibility of the hosts and we have complete faith in the arrangement being made by them."

The West Bengal government's home secretary, Prasad Ranjan Ray, told the Hindu the email - sent from Delhi to a TV channel - would not affect the match and "it would be held on schedule". The Subsidiary Intelligence Bureau and the country's top espionage agency, the Research and Analysis Wing, were investigating the matter, he added.