Patriarch Kirill, the leader of the 135-million-member Russian Orthodox Church, has urged new Polish President Bronislaw Komorowski to support unity between the two countries in cooperation with ecclesiastical bodies.

"Russia, Ukraine, Belarus and Poland are united by many things: Slavic brotherhood, Christian tradition, common history including the sorrowful events of the 20th century sealed in the blood given by our peoples' sons and daughters," Kirill said in a congratulatory message sent to Komorowski on Thursday.

"Remembering the past and thinking about the future the Russian Orthodox Church in cooperation with the Roman Catholic Church in Poland is exerting efforts to strengthen good relations between our two countries," Kirill noted. "I hope you will make a weighty contribution to this important task."

Officials from the Russian Orthodox Church and the Polish Catholic Church have recently been in serious talks about cooperating together.

Last month, they agreed to draft a joint document that would express their shared Christian vision.

"Our aim is to call for mutual forgiveness and reconciliation so the errors of the past are not repeated in the future," said Archbishop Hilarion Alfeyev, head of the Russian Orthodox Church's external relations department, according to Reuters. "Our aim is to seek those things common to us both… such as Christian history."

The church's efforts coincide with those of political officials from both countries who have been trying to thaw relations since April's tragic death of former Polish President Lech Kacyznski, who died in a plane crash.

Komorowski took up the interim presidency following Kaczynski's death and was elected on Monday in a narrow victory over Jaroslaw Kaczynski – Poland's former prime minister and twin brother of the deceased president.

"I congratulate the victor," Kaczynski said following the election.

Komorowski, who is Catholic and a part of the free market supporting Civic Platform party, is expected to help push through reforms started by his party colleague Prime Minister Donald Tusk who is aiming to uproot the country's communist policies.

Kirill noted that the people of Poland associate Komorowski with "a hope for prosperity and stability as well as development of friendly relations with neighbouring states."

"I wish you physical strength, God's help and success in the service you are to carry out on the high and important post of President of Poland," he said.

Komorowski will serve in office for a five year term.