Egyptian President Mohammed Morsi has ordered the military to maintain security and protect state institutions in the run-up to a controversial referendum on a new constitution, BBC informs. The army has also been given the power of arrest.Mr Morsi has tried to calm public anger by annulling a decree giving him huge powers, but rejected a call to scrap the 15 December constitutional vote. Opposition leaders rejected the move and called for protests on Tuesday. The opposition was “not aiming at toppling the president” but wanted a better constitution, former Foreign Minister Amr Moussa told the BBC. Islamist groups have said they will hold counter demonstrations, raising fears of further bloody clashes on the streets of the Egyptian capital.In another apparent concession, the president suspended a big tax increase on the sale of a variety of goods including soft drinks, cigarettes and beer.