CAIRO - Struggling to subdue continuing street protests, the government of President Mohamed Morsi has approved legislation reimposing martial law by calling on the armed forces to keep order and authorizing soldiers to arrest civilians, Egypt's state media reported on Saturday.

Mr. Morsi has not yet issued the order, the flagship state newspaper Al Ahram reported. But even if merely a threat, the preparation of the measure suggested an escalation in the political battle between Egypt's new Islamist leaders and their secular opponents over an Islamist-backed draft constitution. The standoff has already threatened to derail the culmination of Egypt's promised transition to a constitutional democracy nearly two years after the revolt against the former leader Hosni Mubarak.