* Measure limited to referendum period
* Troops will then return to barracks - Mursi's spokesman
By Marwa Awad
CAIRO, Dec 10 (Reuters) - Egypt's government has temporarily given the military the authority to arrest civilians to help safeguard a constitutional referendum planned for Saturday, the official gazette said.
The order, gazetted late on Sunday, said the military would support police and liaise with them to protect "vital institutions" until the referendum result is declared.
The decree gave army officers the right to make arrests and transfer detainees to prosecutors.
Despite its limited nature, the edict will revive memories of Hosni Mubarak's emergency law, also introduced as a temporary expedient, under which military or state security courts tried thousands of political dissidents and Islamist militants.
But a military source stressed that the measure, introduced by a civilian government, would have a short shelf-life.
"The latest law giving the armed forces the right to arrest anyone involved in illegal actions such as burning buildings or damaging public sites is to ensure security during the referendum only," the military source said.
"The armed forces secured polling stations during previous elections when it was in charge of the country," the source said, referring to 16 months of army rule after Mubarak fell.
"Now the president is in charge. In order for the armed forces to be involved in securing the referendum, a law had to be issued saying so," the source added.
Presidential spokesman Yasser Ali said the committee overseeing the vote had requested the army's assistance.
"The armed forces will work within a legal framework to secure the referendum and will return (to barracks) as soon as the referendum is over," Ali said.
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 Mohamed Mursi, but 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 took over after a popular revolt ended Mubarak's 30 years of army-backed rule last year. It then handed power to Mursi, who became Egypt's first freely elected leader in June. The military has not intervened in the latest crisis.
The army statement said the military's duty was to protect national interests and secure vital state institutions.
"The armed forces affirm that dialogue is the best and only way to reach consensus," it added. "The opposite of that will bring us to a dark tunnel that will result in catastrophe and that is something we will not allow."
Hassan Abu Taleb of the Al Ahram Center for Political and Strategic Studies said Saturday's army statement suggested the military wanted both sides to talk out their differences, but discounted the chance of direct military intervention.
"They realise that interfering again in a situation of civil combat will squeeze them between two rocks," he said.