Pope Francis will pray side-by-side with Orthodox Patriarch of Constantinople Bartholomew in Jerusalem in a powerful sign of Christian unity during his May visit to Holy Land, the Vatican said on Thursday. The prayer will take place in the Church of the Holy Sepulchre, built over the spots widely believed to be the sites of the crucifixion, burial and resurrection of Jesus. The two will also sign a joint declaration when they meet on what will be the 50th anniversary of a visit to Jerusalem by two of their predecessors, Pope Paul VI and Patriarch Athenagoras. "We are called to be one, and the pope is coming to remind us of this and renew the spirit of unity and fraternal love," Latin Patriarch Fuad Twal told reporters in Jerusalem as he announced the programme of the pontiff's May 24-26 visit to Israel, Jordan and the Palestinian Territories. During the brief trip, Francis will celebrate Sunday mass in the West Bank city of Bethlehem, where Jesus is believed to have been born. He will meet Palestinian and Syrian refugees and visit the Yad Vashem Holocaust memorial. But Twal warned the visit could be jeopardised if a strike by staff at Israel's foreign ministry, demanding better wages and working conditions, is not resolved in time. "If the strike goes on for two months, I don't think we can make the visit to Israel, but for sure the visit will be done in Jordan and Palestine," said Twal, the Holy Land's senior Roman Catholic prelate. However, Father David Neuhaus, who represents Hebrew-speaking Catholics in Israel, said the government had pledged the visit would not be affected. "Israel has given assurances, both from the prime minister's office and from the office of the foreign minister, that the strike will not affect the visit," he said. Foreign Minister Avigdor Lieberman's spokesman confirmed Neuhaus's remarks. But a spokeswoman for the foreign ministry's labour union insisted that if the strike was not resolved, they would not facilitate the visit. "As long we are on strike, we are not attending to the Pope’s visit," she told AFP, indicating that a preparatory visit by Vatican officials, due to take place earlier this month, was cancelled because of the industrial action. Twal also addressed disappointment among Catholics in the Galilee and Nazareth, who had hoped the pope would visit these religiously significant sites in northern Israel, saying he "agreed with them". "We hope that in the future this visit can take place," the patriarch said. The Argentine pontiff's predecessor, Benedict XVI, visited Israel and the Palestinian territories in 2009. Israel and the Vatican first established full diplomatic relations in 1993, but have been engaged in years of thorny diplomatic negotiations over property rights and tax exemptions for the Catholic Church, which have yet to be fully resolved.