At least 36 people were killed and more than 100 injured in bomb attacks on two Coptic churches on Palm Sunday (April 9), in the latest assault on a religious minority increasingly targeted by Islamist militants.

Islamic State claimed responsibility for the attacks, which come a week before Easter and in the same month that Pope Francis is scheduled to visit Egypt.

The first bombing, in Tanta, a Nile Delta city less than 100 kilometres outside Cairo, killed at least 25 and injured at least 78, Egypt's Ministry of Health said.

The second, carried out just a few hours later by a suicide bomber in Alexandria, hit the historic seat of the Coptic Pope, killing 11, including three police officers, and injuring 35, the ministry added.

Pope Tawadros, who had attended mass at Saint Mark's Cathedral, was still in the building at the time of the explosion but was not harmed, the Ministry of Interior said.

The bombings come as Islamic State's branch in Egypt appears to be stepping up attacks and threats against Christians.