Egypt's army has removed President Mohammed Morsi from power, suspended the constitution and pledged new elections following mass protests, BBC News reported.

The army chief announced the move in a TV address. The head of the constitutional court is expected to be sworn in as interim leader on Thursday, July 4.

Morsi's supporters denounced the move as a military coup and said he was being held in detention. His opponents celebrated through the night in Cairo's Tahrir Square. But officials from Morsi's Muslim Brotherhood said its main rally in Cairo had come under attack by armed assailants and there were reports of deadly clashes elsewhere.

U.S. President Barack Obama said he was "deeply concerned" by the latest turn of events and called for a swift return to civilian rule.

The military moved quickly after the TV address by army chief Gen Abdul Fattah al-Sisi, who said Morsi, Egypt's first freely elected president, had "failed to meet the demands of the Egyptian people".

Military vehicles were seen fanning out across the capital.

Muslim Brotherhood media spokesman Gehad el-Haddad told the BBC that Mr Morsi had been put under house arrest and the "entire presidential team" was in detention.

Haddad's father, senior Morsi aide Essam el-Haddad, and Saad al-Katatni, head of the Brotherhood's political wing, were among those held.

State-run al-Ahram newspaper reported that arrest warrants had been issued for 300 leaders and members of the Muslim Brotherhood.

Haddad said a crowd of some 2,000 Morsi supporters had been shot at by men in civilian dress with machine guns at the main Brotherhood rally.

A notice on Mr Morsi's Facebook page denounced the army for its "military coup".