London, Sep 18 (DPA) Pope Benedict XVI met British Prime Minister David Cameron and other political leaders on the third day of his official visit to Britain Saturday, as police continued to question six men held on suspicion of a terrorist plot against the pontiff.

However, Scotland Yard said nothing had so far been found to substantiate the allegations made against the men, who are all said to be of North African origin.

Meanwhile, the pope started the day with a private meeting with Cameron, who had been unable to attend official events Thursday due to the funeral of his father.

In advance of the visit, organisers of the papal trip said the pontiff would tell Cameron that he had prayed for his father, Ian, who died during a holiday in France last week, aged 77.

The pope also met with Nick Clegg, the Liberal Democrat leader and deputy prime minister, and Harriet Harman, the acting leader of the opposition Labour Party.

The pontiff will celebrate Mass at Catholic Westminster Cathedral in central London, and lead a prayer vigil in Hyde Park later.

Protests against the visit are also expected, and Vatican observers have said the pope could also meet victims of child abuse in the Catholic church.