Egypt's army chief called for talks on national unity to end the country's mounting political crisis after a vital loan from the IMF was delayed and thousands of pro- and anti-government demonstrators took to the streets.

The meeting scheduled for today afternoon was called in response to an increasingly destabilising series of protests that has unfolded since President Mohamed Mursi awarded himself sweeping powers on November 22 to push through a new constitution shaped by his Islamist allies in a referendum on Saturday.

Armed forces chief and Defence Minister Abdel Fattah al-Sisi called for a meeting of "national unity for the love of Egypt to bring together partners of the country in the presence of the president of the republic", the army spokesman said.

An aide said Mursi had supported the call for talks. The Muslim Brotherhood said it would be there, while the main opposition coalition said it would decide on Wednesday morning whether to attend.

Earlier, the finance minister disclosed that a $4.8 billion (3 billion pounds) International Monetary Fund loan, a cornerstone of Egypt's economic recovery hopes, would be delayed until next month.

The announcement came after President Mohamed Morsi on Monday backed down on planned tax increases, seen as key for the loan to go ahead.

Opposition groups had greeted the tax package, which had included duties on alcoholic drinks, cigarettes and a range of goods and services, with furious criticism.

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 Morsi to postpone a referendum on a newconstitution.

Outside the presidential palace, dozens of protesters succeeded in pushing down two giant concrete blocks forming a small part of a wall blocking access to the site.

There was no violent confrontation.

Thousands of flag-waving Islamist Morsi supporters, who want the vote to go ahead as planned on Saturday, assembled at a nearby mosque, setting the stage for further street confrontations in a crisis that has divided the nation of 83 million.

The competing demonstrations carried the risk of further violence, after street clashes last week between opposition and Islamist supporters left seven people dead and hundreds hurt.

Morsi has ordered the army to support police in keeping security during the protests and until results are given from the referendum, which is due to take place on Saturday.

The army's role in the crisis could prove decisive. Thus far, it has sought to remain neutral.