Greece's openly atheist Prime Minister Alexis Tsipras has held tense a meeting with the head of Russia's Orthodox Church while he was on a visit to seek closer ties with Moscow.

Tsipras greeted Patriarch Kirill, who has a close relationship with Russian President Vladimir Putin, with a strained smile at his official monastery residence.

It followed a two-day offensive to charm the Kremlin, Agence France-Presse reported on April 10.

When Tsipras was on February 21 after his Syriza party won the elections in Greece, he chose not to take a religious oath at the ceremony in the country where the Greek Orthodox Church has strong roots.

Tsipras, whose left-wing party has opposed austerity measures as a crippling imposition by the European Union, broke from tradition when he decided to take a civil, rather than a biblical oath.

Newsweek reported in February that a religious icon of Jesus in a small village in Greece had been "weeping" ever since Syriza won the Greek elections at the end of January, witnesses say.

It cited Corinth TV and the Athens-Macedonian News Agency, which said the icon, which dates from early in the 20th century and is housed in the church of St. Nicholas in the village of Asprokampos, Corinthia, had been secreting an oily liquid Tsipras, stormed to power on January 26.

EUROPEAN ATHEIST LLEADERS

The digital news site Quartz had reported it had identified at least two other European leaders who have also said they are atheists - French President Francois Hollande and Croatian Prime Minister Zoran Milanović.

In Moscow Kirill congratulated Tsipras on his election win, but according to AFP, he promptly pressed the prime minister to take on a moral as well as political role in national life.

"I hope that your government will do all it can to preserve the spiritual foundations and morality of your people," the patriarch said.

"Don't forget that being Christian is not a political stance," he noted, saying that only with a "spiritual base" could a country hope for true social justice.

The AFP report said Tsipras was clearly exasperated and said that said that he was glad the religious leader had "taken the time do some research on my personal convictions."

In post-communist Putin's Russia as in Greece the Orthodox church and the State are closely intertwined.

Greece and Russia both have devout Orthodox Christian populations, with ecclesiastical hierarchies sharing close historical ties.

Although the meeting was strained Kirill and Tsipras had some common ground.

In their meeting lasting less than one hour the pair also agreed on the need to put an end to the EU-imposed sanctions said to have badly hit Russia's economy since it seized Crimea and was accused of supporting separatist rebels in Ukraine during 2014.

The Russian Orthodox Church has become one of the bulwarks of President Vladimir Putin's return to traditionalism and conservative values, The Moscow Times reported on April 7.

Putin is known to have close ties to Kirill and is seen attending Orthodox church services, something he might not have officially done during his days serving in the KGB during the Soviet era, which espoused atheism.

While the federal government's burgeoning reliance on the Russian Orthodox Church "is a tool aimed at consolidating society, in using it the authorities risk giving the clergy too much power, an issue that may eventually backfire against the Kremlin, experts told The Moscow Times.

"When the economy is in crisis, [regional governments] need the Church, because it often has more legitimacy among the local populations.

"Imagine if a governor comes out and tells people that there is no money to pay pensions, and then imagine if a priest comes out and says that though money may be scarce, people still need to rally around the national leader, to defend against an external enemy: who do you think people will find more credible?" Alexei Malashenko, chair of the Carnegie Moscow Center's Religion, Society and Security Program, told The Moscow Times.