U2 frontman Bono was at the Vatican last week for a meeting with the pope during which the two discussed the sex abuse scandal plaguing the Catholic Church.

Bono met the pope during a visit to the Vatican to sign an agreement between his charity, ONE, and the Scholas Occurentes educational charity.

Bono told reporters that some of the issues they discussed during their private meeting included sustainable development and 'the wild beast that is capitalism', the Associated Press reports.

The sex abuse scandal rocking the Church also arose during the meeting and Bono said they discussed his feelings on the matter.

Although he did not disclose the pope's exact comments from the meeting, Bono said 'you can see the pain in his face, and I felt he was sincere'.

He added that Pope Francis was 'aghast' about sex abuse in the Catholic Church.

Bono told reporters: 'I explained to him how it looks to some people like the abusers are being more protected than the victims.'

Nonetheless, Bono said the pope was 'an extraordinary man for extraordinary times'.

The pope has come under fire over his handling of the scandal around abuse and subsequent cover-ups by leaders in the Church. The crisis extends across multiple countries, including the US, Chile, Ireland and Australia.

Some critics feel that the pope has not done enough to address the scandal and one former Vatican official has called for his resignation, claiming that the pope knew of allegations of abuse by a US cardinal. 

A new Gallup poll found that the pope's approval ratings have taken a tumble in the past few weeks in the US, where investigations into abuse have dominated recent headlines. 

The percentage of Americans who view Pope Francis favourably fell from 66 per cent in August to 53 per cent this month.