The White House on Sunday extended congratulations to Egyptian president-elect Mohamed Morsi, calling on him to take steps to advance national unity.

White House spokesman Jay Carney also described the election as a "milestone" in Egypt's transition to democracy.

"We look forward to working together with President-elect Morsi and the government he forms, on the basis of mutual respect, to advance the many shared interests between Egypt and the United States," he said in a statement.

"We believe that it is important for President-elect Morsi to take steps at this historic time to advance national unity by reaching out to all parties and constituencies in consultations about the formation of a new government," he added.

As the candidate of Egypt's Muslim Brotherhood, Morsi won 51.73 percent of all the votes in the run-off polls, defeating his rival Ahmed Shafiq, who got 48.27 percent.

Tens of thousands of Morsi's supporters had gathered in Tahrir Square in downtown Cairo for six days against the dissolution of parliament and the military's supplementary constitutional declaration. The declaration consolidated the military's power and imposed limits on the president's power.

The new president will take office without a new constitution and parliament. The ruling Supreme Council of the Armed Forces reportedly will issue a supplementary constitutional declaration to make arrangements for the coming period.

The SCAF, which took over power in February 2011 after the fall of long-time leader Hosni Mubarak in anti-government protests, has affirmed it would hand over power to the new president before the end of June.

Expressing hope for the completion of a transition to a democratically-elected government, Carney stated that "We believe it is essential for the Egyptian government to continue to fulfill Egypt's role as a pillar of regional peace, security and stability. "