India on Friday slammed Pak for not responding through proper channel and felt that Islamabad was doing it deliberately to hide the truth, while continuing to build world pressure against Pak, New Delhi is also preparing a list of Pakistan-based terrorists and terror groups involved in attacks in India and is planning to approach the UN Committee on Terrorism to seek a ban from the world body on them. The list will include Jaish-e-Mohammad chief Masood Azhar and those behind various terror attacks in India like the serial train blasts in Mumbai in July 2006. "We have not received any information from Pakistani authorities through proper channel. Whatever we are hearing like you is through the media. This is not the way a government can respond," External Affairs Minister Pranab Mukherjee told reporters here. "We expect them (Pakistan) to investigate and let us know the outcome of that investigation. Till now we have not received any information from Pakistan," Mukherjee said. Dubbing Pakistan's response so far "totally unacceptable", official sources said if such an approach continues, Islamabad will lose even the "shred of credibility" it has. Making it clear that New Delhi cannot let perpetrators of the Mumbai carnage go scot-free, the sources said India is keeping its options on dealing with Pakistan open but refused to spell them out. The "signs" of the last few days are "not good", the sources said while referring to confusing and varying kinds of reports emanating from Pakistan. They felt that the confusing reports and unsubstantiated stories are being spread by the "powerful" people in Pakistan's establishment who need to cover up their deeds. New Delhi is convinced that ISI and other elements in Pakistani establishment were involved in the Mumbai attacks, arguing that Lashkar-e-Taiba could not have carried out such commando-style strikes without such a collusion. "They (elements in Pakistani establishment) are trying to hide facts and doing what a guilty person will do," a source said, adding the behaviour proves part of the guilt. "I will be amazed if they do come clean on the Mumbai attacks," the source said while noting that it was a remote possibility given the suspicion that elements in establishment are involved. New Delhi apprehends that Islamabad may even duck a direct response to India's evidence or drag the issue by seeking clarifications. India feels there are many power centres within Pakistani establishment and such a situation leads to complications when it comes to dealing with a government. While weighing options of dealing with Pakistan, India is clear that its actions needed to be calibrated in such a manner that these target "that part of Pakistan which was responsible for Mumbai attacks" and not hurt common people of that country.