Security and hospital officials say clashes between supporters and opponents of Egypt's Islamist president have killed at least one person and injured scores.

The violence in the coastal city of Masoura, north of Cairo, began Wednesday when opponents of President Mohammed Morsi pelted his supporters with garbage as they gathered outside a mosque to stage a march to back the president.

The officials spoke on condition of anonymity because they were not authorized to speak to reporters

Clashes between the two sides have grown in frequency over the past few days during the buildup for June 30 protests by the opposition to try to force Morsi out.

Morsi, who completes his first year in office June 30, was due to address the nation later on Wednesday.