Portugal's famed street artist, Bordalo II, has broken into a Lisbon venue where Pope Francis will celebrate a mass next week and rolled out a huge carpet of oversized banknotes to criticise how much the state has spent on the event.

Francis will travel to Lisbon from Aug. 2-6 to attend the World Youth Day global gathering of young Catholics, which is expected to bring together hundreds of thousands of pilgrims. 

Bordalo II, known for his political art pieces often made from garbage, shared pictures and videos of the carpet, featuring humongous 500-euro ($551) notes, being rolled out down the venue's stairs on Thursday in a protest he described as the "walk of shame".

"At the time when many people are fighting to keep their homes, their work and their dignity, millions worth of public funds have been invested to sponsor the (papal) tour," the artist, whose real name is Artur Bordalo, wrote on Instagram. 

Official estimates in January showed the event would cost 161 million euros, to be paid by the government, the Catholic Church, the city council of Lisbon and nearby Loures. 

A number of public figures and politicians have criticised the Portuguese state for its share of the expenditure, which the government put at 30 million euros in January, as millions of Portuguese face galloping inflation.

Earlier this year, heavy criticism forced the Lisbon city council to cut planned spending on an altar for Francis to celebrate a mass to 2.9 million euros from over 5 million euros.

Asked about Bordalo II's carpet, Lisbon Mayor Carlos Moedas told reporters the artist used his voice to express his concerns and that such protests were normal for these events.