An Egyptian opposition alliance rejected on Tuesday what it described as the "oppressive practices" of the prosecutor general and the Muslim Brotherhood against political activists and peaceful protesters.

"Reports filed against activists and revolutionary leaders are of pure political nature and aim at suppressing the opposition," said a statement issued by the National Association of Revolutionary Forces.

The prosecutor general, Talaat Ibrahim, ordered on Monday the arrest of five leading activists on charges of instigating violent clashes by calling for protests outside the Muslim Brotherhood's headquarters on Friday.

The statement said, "The prosecutor general's quick response to the claims against activists compared to his complete disregard of lawsuits filed against the Muslim Brotherhood's Supreme Guide is rather surprising."

The statement added that his quick response suggests that the prosecutor general favors the Brotherhood.

Meanwhile, protesters gathered on Tuesday outside Cairo's High Court in solidarity with the summoned activists, reported a local newspaper.

The protesters chanted against the prosecutor general, saying that he belongs to the Muslim Brotherhood, according to Shorouk newspaper.

They pointed to his appointment through a controversial decree issued by President Mohamed Mursi, who hails from the Islamist group.

Members of April 6 youth movement, Dostour Party and the Popular Alliance joined the protesters, expressing anger at  the arrest warrants issued against the prominent politicians.