Pakistan Prime Minister Raja Pervez Ashraf was ordered on Wednesday to appear before the Supreme Court this month over his failure to comply with orders to reopen corruption cases against President Asif Ali Zardari.The move, another twist in a long-running standoff between the government and the judiciary, could lead to further political instability in Pakistan.Two months ago, Ashraf’s predecessor, Yusuf Raza Gilani, was found guilty of contempt over the same issue and disqualified from holding the post of prime minister. "We hereby issue a notice to Prime Minister Raja Pervez Ashraf ... to show cause why he may not be proceeded against for committing contempt,” the court said."He shall appear in person on the next date of hearing.”The court adjourned proceedings until August 27.The summons could lead to Ashraf being formally charged with contempt and disqualified, dealing another blow to the ruling Pakistan People’s Party (PPP).But the move is unlikely to lead to the collapse of the coalition government because it has a comfortable majority in parliament to elect another prime minister.Thousands of corruption cases were thrown out in 2007 by an amnesty law passed under former military president Pervez Musharraf, paving the way for a return to civilian rule.