Egypt's government has temporarily given the military the authority to arrest civilians to help safeguard a constitutional referendum planned for next Saturday.

The order, which a presidential official and military source confirmed, said the military would support and coordinate with police to protect "vital institutions" temporarily until the referendum result.

The decree gave army officers the right to conduct arrests and to transfer detainees to prosecutors.

Despite its limited nature, the edict will revive memories of Hosni Mubarak's emergency law, under which military or state security courts tried thousands of political dissidents and Islamist militants.

A cabinet source said ministers had reviewed the decree last week.

It said troops had secured elections during a military-run transition after Mr Mubarak, but with a civilian president now in charge they needed a decree to allow them to play that role.

On Saturday, the military urged rival political forces to solve their disputes via dialogue and said the opposite would drag the country into a "dark tunnel", which it would not allow.

A statement issued by the military spokesman and read on state radio and television made no mention of President Mohammed Mursi.

The statement said a solution to the political crisis should not contradict "legitimacy and the rules of democracy".

A military source close to top officers said the statement "does not indicate any future intervention in politics".

A military council ran Egypt for 16 months after a popular revolt ended Mr Mubarak's 30 years of military-backed rule last year.

The armed forces have not intervened in the latest crisis.

The army statement said the military's duty was to protect national interests and secure vital state institutions.