DAR ES SALAAM (AFP) - United States President Barack Obama called President Mohamed Mursi to warn him that the voices of all Egyptians must be heard as a political crisis escalates, the White House said on Tuesday.

Mr Obama placed the call from Tanzania, on the final stop of his African tour and told him Washington was committed to "the democratic process in Egypt and does not support any single party or group", the official said.

"He stressed that democracy is about more than elections; it is also about ensuring that the voices of all Egyptians are heard and represented by their government, including the many Egyptians demonstrating throughout the country," the White House said.

The White House's public description of the contents of the call mirrored Mr Obama's own remarks on Monday when he voiced concern in a press conference about Egypt amid mass protests and an apparent threat to Mr Mursi's rule.

"President Obama encouraged President Mursi to take steps to show that he is responsive to their concerns, and underscored that the current crisis can only be resolved through a political process," the statement went on.

"As he has said since the revolution, President Obama reiterated that only Egyptians can make the decisions that will determine their future."

As he did publicly during a press conference in Tanzania on Monday, Mr Obama also used the call the underscore "deep concern" about violence during demonstrations, especially sexual assaults against women, the White House said.

"He reiterated his belief that all Egyptians protesting should express themselves peacefully, and urged President Mursi to make clear to his supporters that all forms of violence are unacceptable.

"Finally, the president noted that he is committed to the safety of US diplomats and citizens in Egypt and stressed his expectation that the government of Egypt continue to protect US diplomatic personnel and facilities."

Mr Obama's call came after the army warned Islamist president Mursi it would intervene if he failed to meet the demands of the people within 48 hours.

In a statement, the Egyptian presidency said the army declaration, which had not been cleared by the presidency, could cause confusion, and the presidency would continue on its own path towards national reconciliation.