By Yasmine Saleh and Marwa Awad
CAIRO, Dec 11 (Reuters) - A vital $4.8 billion International Monetary Fund loan to Egypt will be delayed until next month, its finance minister said on Tuesday, intensifying the political crisis gripping the Arab world's most populous nation.
As rival factions gathered in Cairo for a new round of demonstrations, Finance Minister Mumtaz al-Said said the delay in the loan agreement was intended to allow time to explain a heavily criticised package of economic austerity measures to the Egyptian people.
The announcement came after President Mohamed Mursi on Monday backed down on planned tax increases, seen as vital for the loan to go ahead, within hours of their being announced. Opposition groups had greeted the tax package, which included duties on alcoholic drinks, cigarettes and a range of goods and services, with furious criticism.
"Of course the delay will have some economic impact, but we are discussing necessary measures (to address that) during the coming period," the minister told Reuters, adding: "I am optimistic ... everything will be well, God willing."
Prime Minister Hisham Kandil added: "The challenges are economic not political and must be dealt with aside from politics."
On the streets of the capital, tensions ran high after nine people were hurt when gunmen fired at protesters camping in Tahrir Square, according to witnesses and Egyptian media.
The opposition has called for a major demonstration it hopes will force Mursi to postpone a referendum on a new constitution.
Supporters of the Islamist leader, who want the vote to go ahead as planned on Saturday, gathered in the capital, setting the stage for further street confrontations in a crisis that has divided the nation of 83 million.
The upheaval following the fall of Hosni Mubarak last year is causing concern in the West, in particular the United States, which has given Cairo billions of dollars in military and other aid since Egypt made peace with Israel in 1979.
The turmoil has also placed a big strain on the economy, sending foreign currency reserves down to about $15 billion, less than half what they were before the revolt two years ago.
Police cars surrounded Tahrir Square in central Cairo, the first time they had appeared in the area since Nov. 23, shortly after a decree by Mursi awarding himself sweeping temporary powers that touched off widespread protests.
The attackers, some masked, also threw petrol bombs that started a small fire, witnesses said.
"The masked men came suddenly and attacked the protesters in Tahrir. The attack was meant to deter us and prevent us from protesting today. We oppose these terror tactics and will stage the biggest protest possible today," said John Gerges, a Christian Egyptian who described himself as a socialist.
The latest bout of unrest has so far claimed seven lives in clashes between the Islamist Muslim Brotherhood and opponents who are also besieging Mursi's presidential palace.
The elite Republican Guard which protects the palace has yet to use force to keep protesters away from the graffiti-daubed building, now ringed with tanks, barbed wire and concrete barricades.
The army has told all sides to resolve their differences through dialogue, saying it would not allow Egypt to enter a "dark tunnel". For the period of the referendum, the army has been granted police powers by Mursi, allowing it to arrest civilians.
The army has portrayed itself as the guarantor of the nation's security but so far it has shown no appetite for a return to the bruising front-line political role it played after the fall of Mubarak, which severely damaged its standing.
Leftists, liberals and other opposition groups have called for marches to the presidential palace later on Tuesday to protest against the hastily arranged constitutional referendum planned for Dec. 15, which they say is polarising the country and could put it in a religious straightjacket.
Mohamed ElBaradei, a prominent opposition leader and Nobel prize winner, called for dialogue with Mursi and said the referendum should be postponed for a couple of months due to the chaotic situation.
"This revolution was not staged to replace one dictator with another," he said in an interview with CNN.
Outside the presidential palace, anti-Mursi protesters huddled together in front of their tents, warming themselves beside a bonfire in the winter air.
"The referendum must not take place. The constitution came after blood was spilt. This is not how a country should be run," said Ali Hassan, a man in his 20s.
Opposition leaders want the referendum to be delayed and hope they can get sufficiently large numbers of protesters on the streets to change Mursi's mind.
Islamists, who dominated the body that drew up the constitution, have urged their followers to turn out "in millions" in a show of support for the president and for a referendum they feel sure of winning.
The opposition says the draft constitution fails to embrace the diversity of the population, a tenth of which is Christian, and invites Muslim clerics to influence lawmaking.
Mahmoud Ghozlan, the Muslim Brotherhood's spokesman, said the opposition could stage protests, but should keep the peace.