(BBC News) Egyptian President Mohammed Mursi has said his move to order the retirement of two of the country's top generals was for "the benefit of this nation".

He was speaking after replacing the powerful head of the armed forces, Field Marshal Mohammed Hussein Tantawi, and the chief-of-staff, Gen Sami Annan.

Mr Mursi is said to have issued a new constitutional declaration giving him broad legislative and executive powers.

The generals assumed presidential powers after the fall of Hosni Mubarak.