A protester stands behind an Egyptian flag during a protest in front of the presidential palace in Cairo December 4, 2012. REUTERS/Asmaa Waguih ----------------- (Reuters) - Egyptian President Mohamed Mursi returned to work in Cairo on Wednesday, although scores of protesters angered by his drive to push through a new constitution were still blocking one gate of the presidential palace. The Islamist leader left the palace in the northern Cairo district of Heliopolis on Tuesday evening as tens of thousands of demonstrators surged around it, clashing briefly with police. A presidential source said Mursi was back at work in the palace, even though up to 200 demonstrators had camped out near one entrance overnight. Traffic was flowing normally in the area where up to 10,000 people had protested the night before, and riot police had been withdrawn, a Reuters witness said. The rest of the Egyptian capital was calm, despite the political furor over Mursi's November 22 decree handing himself wide powers and shielding his decisions from judicial oversight. The Islamist leader says he acted to prevent courts from derailing a newly drafted constitution that will go to a referendum on December 15, after which Mursi's decree will lapse. The Health Ministry said 18 people had been wounded in the clashes on Tuesday. While they fired tear gas when protesters broke through barricades to reach the palace walls, riot police appeared to handle the disturbance with restraint. "Our demands from the president: retract the presidential decree and cancel the referendum on the constitution," read a placard hung by demonstrators on a palace gate. The crowds had gathered in what organizers had dubbed a "last warning" to Mursi. "The people want the downfall of the regime," they chanted, roaring the signature slogan of last year's uprising that toppled President Hosni Mubarak. But the "last warning" may turn out to be one of the last gasps for a disparate opposition which has little chance of stopping next week's vote on a constitution drafted over six months and swiftly approved by an Islamist-dominated assembly. Facing the gravest crisis of his six-month-old tenure, the Islamist president has shown no sign of buckling under pressure, confident that the Muslim Brotherhood and its Islamist allies can win the referendum and a parliamentary poll to follow. (Additional reporting by Tom Perry; Writing by Alistair Lyon; Editing by Janet Lawrence)