Prime Minister Syed Yousuf Raza Gilani has said that foreign hand may be involved in recent incidents of violence in Karachi. Talking to journalists here in Multan on Friday, prime minister said the government would take strict action against anyone who challenges its writ and violates the law. Responding about President Obamas remarks about Pakistan, Gilani said the civil government, its institutions, including the judiciary; media were all strong and working under the constitution. Regarding the operation in parts of NWFP, the prime minister said whenever the writ of the government is challenged, the provincial government can requisition the services of the armed forces for its support.