UNITED NATIONS (AFP) - Egypt's army-backed government pleaded Saturday for support for its crackdown on the Muslim Brotherhood, warning that the world must not justify "terrorism."

Foreign Minister Nabil Fahmy made his appeal in a speech at the annual United Nations General Assembly as hundreds of flag-waving protesters staged a noisy rally against him outside the global body's headquarters.

Mr Fahmy said that Egyptians "have the right" to carry out a political roadmap announced after the July 3 ouster of elected president Mohamed Mursi and urged "non-interference" from the outside world.

"I trust that the international community, which has long rejected terrorism, will firmly stand by the Egyptian people in the fight against violence and its advocates, and will not accept any attempt to justify it, or tolerate it," Mr Fahmy said.

Egypt has been wracked by violence since the army ousted Morsi, an Islamist who was Egypt's first elected leader.

Police have arrested more than 2,000 Islamists in a broad crackdown on Mursi's Muslim Brotherhood movement.

More than 1,000 people, mostly Islamists, have also died in clashes with security forces since Aug 14, when police broke up two Islamist protest camps in Cairo.

Since the bloody crackdown, Islamists have lashed out at the Coptic Christians with a series of church attacks, accusing the minority of backing the military.

In his speech, Mr Fahmy condemned "hideous acts of terrorism" that "aim at undermining the democratic process and destroying our economy." The army-installed government has drafted a roadmap that calls for new elections in 2014.

Egypt's crackdown has been widely criticised by Western nations, but has won support from several regional governments wary of the Arab Spring protests.

The United States has stopped short of cutting its US$1.55 billion (S$1.94 billion) in annual military and economic aid to Egypt.