Video and pictures showed the two women at the back of the centre aisle of the Basilica of St. Paul Outside the Walls, where the pope and other Christian leaders were taking part in a traditional annual service for Christian unity.

One of the women held up a banner reading "Stop Blessing Corridas" and wore a T-shirt with the same slogan in Italian. Corrida is the Spanish word for a bullfight.

It was not clear if the pope heard the women, who were at the back of the church, which is in Rome's outskirts.

The ceremony, which was attended by Archbishop of Canterbury Justin Welby, spiritual leader of the world's Anglicans, went ahead without interruption before about 1,500 people. Both the pope and Welby went on to deliver their homilies.

The women were from the Italian branch of the organisation People for the Ethical Treatment (PETA), witnesses said.

Members of the same group gathered near the Vatican last July in red capes and fake horns to urge the pope to denounce what they see as the barbaric practice of bullfighting. The practice does not exist in Italy.

(Reporting by Gugielmo Mangiapane and Philip Pullella; Editing by Frances Kerry)