ISLAMABAD - The opposition on Thursday in the Senate sought an explanation from Attorney-General of Pakistan Khalid Jawed Khan for his alleged statement given before the Supreme Court that the federal government was weighing different legal and constitutional options regarding Karachi.  The opposition also staged a protest walkout from the house over alleged clash between PML-N workers and police outside the office of National Accountability Bureau, Lahore, during PML-N Vice President Maryam Nawaz’s appearance before the bureau.  The treasury rejected the allegations saying that it was taking no unconstitutional step and only concerned to improve the situation of the metropolitan city. It also alleged the PML-N for setting a new tradition by attacking the office of the top anti-corruption watchdog in the provincial capital of Punjab. PPP stalwart Senator Mian Raza Rabbani speaking in the house, during the especially summoned session to clear the FATF-related legislation, said that the attorney-general should be summoned for his clarification on his statement about Karachi, the provincial capital of Sindh, as the matter was serious in nature.