Police in Mumbai have accused a serving officer in the Pakistan Army of being involved in the terrorist attacks on the city that killed more than 170 people in November.

The move represents the first time India has accused an individual linked to the Pakistani state of playing a role in the Mumbai atrocities, a development that will place yet more strain on the tense relationship between the two nuclear-armed neighbours.

The document detailing the charges against Azam Amir Kasab, the sole gunman to be captured alive, accuses Colonel Saadat Ullah of helping to set up the phone network used by the terrorists to speak to their handlers during the attacks. It claims that the officer is part of the Pakistan Army’s Special Communications Organisation (SCO), an offshoot of the signals corps.

Col Ullah was traced using information partly supplied by the FBI, a senior police officer said.

According to police documents obtained by The Times, the ten Islamist militants who rampaged through Mumbai spoke to their handlers in Pakistan during the attacks via mobile phones connected to Callphonex, an internet telephony provider based in New Jersey. The militants’ Callphonex account was set up by an individual who identified himself as Kharak Singh, using the e-mail account kharak_telco@ yahoo.com.

Police claim that this e-mail account was accessed from ten different unique internet locations – or IP addresses – including one used by Col Ullah.

In the mammoth 11,000-page charge sheet filed by police against Kasab, the colonel’s physical address is given as Qasim Road, Rawalpindi, Pakistan, which is the headquarters of the SCO. The document says that Col Ullah and another man, Khurram Shazad, of the same address, “facilitated communication … and hence conspired with [Kasab] in perpetuating the heinous crime”.

The charge sheet also details the involvement of a mastermind figure referred to by the gunmen and their handlers during their attacks only as “Major General Sahab”, who Mumbai police have been unable to identify.

The charge sheet may fall short of providing definitive proof of Col Saadat’s involvement, internet experts said. It is possible to route internet traffic to disguise its origin: other IP addresses used to access the gunmen’s telephone service account were traced to Chicago, Kuwait and Moscow.

The criminal investigation begun by the Mumbai police has identified 37 suspects – including the two army officers – wanted for their alleged involvement in a plot that struck 13 targets across Mumbai, including two luxury hotels and an orthodox Jewish outreach centre, terrorising the city for 60 hours. All but two of the suspects, many of whom are identified only through aliases, are Pakistani.

Ujjwal Nikam, the public prosecutor in the case against Kasab, told The Times that he would give his opening address in the trial, in which he will frame the charges against the 21-year-old, before a special court in Mumbai on March 9.

"I will show that this was a criminal conspiracy hatched in Pakistan and involving henchman of [the Pakistan-based terrorist faction] Lashkar-e-Taiba," he said.

Kasab has been charged with crimes including the waging of war against India and murder. He could be sent to the gallows if convicted.

Mr Nikam said that he was confident of securing a conviction within six months, but that it was too early for him to say whether he would seek the death penalty if Kasab were found guilty.

Kasab was captured on November 26 after he and an accomplice opened fire on commuters at Chatrapati Shivaji Terminus, one of India’s busiest train stations, killing more than 50 people. In a sharp reversal from previous denials, the Pakistan Government admitted last month that he was a Pakistani citizen and that the attacks were at least partly plotted on its soil.

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