One person was killed and 30 injured late Thursday as supporters and critics of Egyptian President Mohamed Morsi clashed in the north of the country, the health ministry reported.
The fighting took place in the northern Nile Delta province of Sharqiya, said the agency, cited by the official MENA news agency.
The clashes broke out in front of the headquarters of the Freedom and Justice Party, the political wing of the Muslim Brotherhood, where Morsi draws his support.
A statement from the FJP posted on its Facebook page said one of its members had been killed.
The clashes came as Egyptian Islamist parties prepared for an open-ended demonstration Friday in support of Morsi, two days before planned rallies against him.
Morsi's legitimacy is at the heart of protests both for and against him.
His supporters say he derives his authority from the first free presidential election in Egypt's history, and that the challenges he faces -- corrupt and inefficient institutions, economic troubles and religious tensions -- were inherited.
His critics see him as a Muslim Brotherhood delegate, favouring Islamists in key positions and returning the country to authoritarianism.