ISLAMABAD — Pakistan’s Supreme Court ordered the arrest of Prime Minister Raja Pervaiz Ashraf in a corruption case Tuesday, in a drastic intensification of hostilities between the country’s embattled government and its opponents.

The court order came as an enigmatic preacher turned politician, Tahir-ul-Qadri, addressed thousands of supporters outside Parliament andrepeated calls for the government’s ouster. In earlier speeches, he said a caretaker administration led by technocrats should take its place.