June 18, 2007 6:09 PM

VATICAN CITY (AP)-Pope Benedict XVI told a visiting Cypriot Orthodox leader Saturday that he holds hope that the Catholic and Orthodox churches can be united, despite centuries of painful division.

The churchmen also explored how the two sides could work together on social, moral and bioethical issues, including same-sex marriage and embryonic stem cell research.

Archbishop Chrysostomos II of Cyprus has offered to play the role of mediator to try to arrange a groundbreaking meeting between the pope and the Orthodox patriarch of Moscow, Alexy II. That encounter eluded the late John Paul II in his long papacy because of Catholic-Orthodox tensions following the demise of Soviet communism.

In a speech to the archbishop after their private session, Benedict said he held "firm hope" of uniting the two churches.

Despite "centuries-old divisions, diverging roads and despite the hard work of closing painful wounds, the Lord has never ceased to guide our steps on the path toward unity and reconciliation," Benedict said.

Chrysostomos told reporters that the chief problem was a lack of communication between the pope and the patriarch. He said he will pursue his offer to help organize a possible meeting when he meets with Alexy in Moscow next month.

The archbishop has contended that Benedict's background as a theologian with a good grasp of Orthodox theology would help the process of reuniting the two churches, which split nearly 1,000 years ago.

He said he left the meeting "with much optimism."

The Russian church accuses Roman Catholics of improperly seeking converts in areas that traditionally would be Russian Orthodox. The Vatican has rejected the allegations, saying it is only ministering to Russia's tiny Catholic community of about 600,000 people in a country of 144 million.

In a joint statement, both leaders pledged to "intensify the search for full unity among all Christians."

The Vatican sees the Orthodox church as a logical partner in its efforts to push its conservative agenda on bioethical, social and moral issues, including opposition to embryonic stem cell research, abortion, euthanasia and same-sex marriage.

Benedict and Chrysostomos signed a joint statement indicating such collaboration was desired.

They expressed "serious worry" about bioethical issues, saying: "There is in fact the risk that certain techniques applied to genetics ... will end up harming the dignity of man."

The statement also expressed concern that humankind, by "putting itself at the center of the universe," endangers the environment.