ISLAMABAD (INP) - The PML-N chief Nawaz Sharif on Thursday called upon the government to constitute an impartial investigation commission over PNS Mehran base attack. The Pakistan Muslim League-Nawaz (PML-N) leader said the government should take the matter seriously as it was looking non-serious about the matter like it was about the Abbottabad episode. Nawaz said this while talking to media persons at Benazir Bhutto International Airport before leaving for Nawabshah to condole with President Asif Ali Zardari the death of his father Hakim Ali Zardari. He regretted that Opposition Leader in the National Assembly Chaudhry Nisar Ali Khan had written a letter to Prime Minister Yousuf Raza Gilani for forming an impartial commission to investigate the US raid in Abbottabad but the premier did not respond. Had the government constituted an independent commission for Abbottabad incident, the attack at PNS Mehran could have been avoided, he said as he demanded the government take concrete steps for protection the countrys sovereignty. Nawaz also expressed his dismay over non-implementation of the joint resolution of the parliament for stopping US drone attacks inside Pakistan. We should carry out self-accountability for improving the situation and reject foreign aid, which is poisonous for the country, Nawaz said. To a question, he said that the government should break the begging bowl immediately, saying that several generations of Pakistan have been burdened by the heavy national debt. Staff Reporter from Lahore adds: PML-N Chief Nawaz Sharif on Thursday could not leave for Nawab Shah from Islamabad to condole with President Asif Ali Zardari. According to Nawaz Sharifs Secretary Asif Kirmani, it was due to bad weather that the aeroplane could not take off, and hence the visit was postponed.