Pope Leo XIV has called for unity at his inaugural Mass at the Vatican, attended by thousands of faithful and world leaders including Ukraine's Volodymyr Zelensky.

During the address on Sunday, he criticised economic systems which he said exploited "Earth's resources" and marginalised the poor.

He also said he would seek to govern "without ever yielding to the temptation to be an autocrat".

The Pope noted efforts to end the war in Ukraine in a prayer after the service and also held a meeting with Zelensky. The pontiff had called for an end to the war in his first days in office.

The Ukrainian leader thanked the new Catholic leader for his "support for Ukraine" and "clear voice in defence of a just and lasting peace".

Earlier on Sunday, the Pope had addressed worshippers in St Peter's Square. Thousands of pilgrims stood in reverence as the pope received the symbols of office, blessed the people and issued a strong call for unity.

The Mass from the first US and Peruvian pontiff also drew attendance from dignitaries including US Vice President JD Vance as well as politicians from Germany to Peru as well as faith leaders and European royals.

"We still see too much discord, too many wounds caused by hatred, violence, prejudice, the fear of difference, and an economic paradigm that exploits the Earth's resources and marginalises the poorest," he said.

In a prayer afterwards, he noted the efforts for a ceasefire in Ukraine, before holding a private audience with Zelensky and his wife.

"The martyred Ukraine is waiting for negotiations for a just and lasting peace to finally happen," Pope Leo said.

Last week, he had offered the Vatican as a venue for possible peace talks after Russian President Vladimir Putin turned down Zelensky's offer to meet face-to-face in Turkey for negotiations.

Prior to giving his Mass, there had been cheers from the crowd when the pontiff appeared in his popemobile as it drove around St Peter's Square and down Via della Conciliazione to the river Tiber and back.

There was a strong sense of excitement in the square. Michelle, from Germany, told the BBC she "came on purpose to see the Pope".

"I arrived yesterday in the morning and I'm leaving in a few hours, so I don't have much time. It's very crazy because there are so many people. I wanted to see the Pope."

Many of the tens of thousands attending were Catholics, but tourists also came to be part of the historic occasion.

Joe from the US state of Missouri said: "We're on vacation, but it's great timing. We're here to see the Pope's inaugural Mass. It's very special. I'm glad we came early."

He said he was "extra proud" to see the first Pope from the United States. "That was a surprise. He's gonna be a wonderful Pope. I am not Catholic, but I grew up Catholic, but this is just inspiring no matter what denomination of Christian you are."

Also in the crowds was Pia, from Chile, a professor of philosophy at the Pontifical University of the Holy Cross in Rome. She told the BBC she felt there was "a new hope in the church".

Pia said that among the Pope's first words when he was elected was "Let the peace be with you", the words of Jesus. And then he said "don't be afraid".

"He knows what the world and the church needs. A church that is preaching hope, preaching peace. I think many people are waiting for that," she said.

The Pope's official inauguration followed the Mass, with a pallium garment - a white woollen band - placed on the Pope's shoulders, and fixed in place with three pins to represent the nails on the cross.

Cardinal Luis Antonio Tagle of the Philippines then placed on the pope's finger the Ring of the Fisherman, a symbol of the papacy which bears an image of St Peter.

Pope Leo then took the book of the gospels to bless the people.