Cairo - Decisive action is needed to prevent sectarian tensions from escalating in Egypt, the country's top Islamic leader said Tuesday in the wake of a fatal riot fanned by Muslim protests over a DVD deemed offensive to their faith.

Grand Imam Mohammed Sayyed Tantawi made the comments after four people were killed when 5,000 Muslims rioted Friday in a Christian neighborhood in Egypt's second-largest city, Alexandria.

"We should take quick action to bridge the chasm as soon as we hear about a conflict erupting between Muslims and Christians," Tantawi, quoting a famous Arabic poem, said as a six-day gathering of Anglican clerics from around the world began in Cairo.

Tantawi, Pope Shenouda III of the Coptic Orthodox Church and the Egyptian government failed to contain Muslim anger over a play performed two years ago by a Christian church in the port city of Alexandria and circulated recently on a DVD.

Tantawi heads the prestigious al-Azhar University, the world's highest seat of learning for Sunni Muslims.

The play, titled "I Was Blind but Now I Can See," angered Muslims as it tells the story of a young Christian who converts to Islam and becomes disillusioned.

Some believed the DVDs were circulated to spark protests by Muslims in Alexandria against a Coptic Christian man who had been nominated by Egypt's ruling National Democratic Party to stand in next month's parliamentary elections.