Pope Francis warns President Obama of excesses of capitalism

President Barack Obama has met Pope Francis at the Vatican for the first time as he continues his European tour dominated by the Ukraine crisis.

President Obama said it was a "great honour" to meet the pontiff and called himself a "great admirer" of Pope Francis as they shook hands before sitting down with their translators for their meeting.

The two spoke for nearly an hour and exchanged gifts, with the pope offering Mr Obama two medallions and a copy of his apostolic exhortation The Joy of the Gospel, where the pontiff criticised trickle down economics, financial speculation and the excesses of capitalism.

"You know, I actually will probably read this when I'm in the Oval Office, when I am deeply frustrated and I am sure it will give me strength and will calm me down," Mr Obama told reporters.

He also invited the pontiff to visit the White House after giving him seeds of fruit and vegetables from the garden of the presidential residence, to which Pope Francis responded in Spanish: Como no! (Of course).

In an interview with Italian daily Corriere della Sera, Mr Obama said the Pope's "moral authority" added weight to his call to readdress income inequality between the richest one per cent of Americans and the 99 per cent.

"In the United States over the last few decades, we've seen a growing gap between the income of those at the very top and the income of the typical family," he said. "But this isn't just a problem for the United States, it's a problem for countries around the world. And it isn't just an economic issue, it's a moral issue."

With his poll ratings under pressure ahead of the midterm elections, Mr Obama will certainly welcome the pope's blessing.

Dr Rebecca Rist, papal expert at the University of Reading, said: "Since Francis is popular with many American Catholics, Obama hopes that at least, this group will stay Democrat in the upcoming mid-term elections, especially as the Democrats run the risk of losing the Senate."

Mr Obama is set to meet Italian prime minister Matteo Renzi and president Giorgio Napolitano later today as he continues his six-day tour across Europe.

His visit comes against the backdrop of Russian intervention in the Crimean peninsula, which the Kremlin officially annexed following a controversial referendum considered "illegal" by the West and Kiev.

Yesterday, Mr Obama launched a robust defence of Western values to counter Moscow's "bullying" in Ukraine and warned further incursions would trigger a fresh round of sanctions.

Earlier, the president said Russia was a "regional power" acting out of weakness, not strength, and called on President Vladimir Putin to de-escalate tensions and change course.

On Monday, world leaders of the G-7, including the US, UK, France, Germany, Italy, Canada and Japan, cancelled a planned G-8 meeting in the Russian city of Sochi.

They will now meet in Brussels- excluding Russia- in June in an effort to isolate Mr Putin from international discussions.