Quoting investigators, Dawn reports that Omar Saeed Sheikh made the hoax calls with an intention of heightening the tension between India and Pakistan.
"It was he who threatened the civilian and military leaderships of Pakistan over telephone. And he did so from inside Hyderabad jail," investigator said, referring to the year-ago reports of a hoax caller claiming to be then Indian foreign minister Pranab Mukherjee making threatening calls to Pakistan President Zardari.
Sheikh, who was in jail, was informed about the Mumbai terror attacks by his wife Saadia Omar on Nov 26 2008. He received the information through a mobile phone which he was using with the knowledge of the wardens, the report states.
He kept receiving information through the UK-registered SIM till Nov 28 night till the time the Indian security forces took the situation under control in Mumbai.
After this, he reportedly made a phone call to Pranab Mukherjee and told an operator handling Mukherjee"s calls that he was the President of Pakistan.
The Indian officials started verification as part of security precautions and the operator informed Sheikh (believed to be Zardari) that Mr Mukherjee would get in touch with him soon.
He later tried to talk to the US secretary of state but failed. After this, he called up Pakistan authorities including Zardari, Prime Minister Yousuf Raza Gilani, Interior Minister Rehman Malik and Gen Kayani.