The Thursday move raises the pressure on the government as it nears the end of its term in office.
The new instruction came a week after the Supreme Court ordered the arrest of the premier in connection with a corruption investigation that dates back to energy projects commissioned when he was water and power minister.
The second case relates to the former head of the oil and gas regulatory authority, Tauqir Sadiq, who fled abroad after being accused of embezzling $850 million in kickbacks and commissions.
Members of the government accuse the court of waging a politically motivated witch hunt against the administration, which in March 2013 will become the first elected civilian government in Pakistan to complete a full term in office.
Last June the court sacked Ashraf's predecessor for contempt over his refusal to ask Switzerland to reopen corruption cases against President Asif Ali Zardari on the grounds that he has immunity as head of state.