Omar Awadallah told Ma'an voting may begin at noon Friday as the global cultural organisation's World Heritage Committee, meeting in Russia, had started discussions on Bethlehem on Thursday, a day earlier than expected.
A Palestinian delegation, headed by Foreign Minister Riyad al-Malki, is working hard to convince the 21-nation committee to add Christian sites in Bethlehem to the world heritage list despite Israeli and US objections to the application, Awadallah said.
To succeed, the bid needs the support of 75 percent of the committee, and Awadallah said the delegation had enlisted the support of 11 countries. He expected the bid to be successful, but cautioned that countries could change their decisions "at the last second."
The PA Foreign Ministry has prepared applications to add another 20 archaeological sites to the World Heritage committee after the vote on Bethlehem, Awadallah said, adding that each country could only admit two sites at a time.
If the current bid to add the Church of the Nativity and nearby Pilgrimage Route is successful, the Palestinian Authority will hold celebrations on July 7, Awadallah said.
PA Minister of Culture Siham Barghouti told Ma'an that Palestinians had a right to preserve cultural and religious places, particularly the Nativity Church, built over a grotto where Christian tradition says Jesus was born.
The 4th century church needs repairs, especially to its roof. The Pilgrimage Route marks the path which tradition says Joseph and Mary took into the city in their trek from Nazareth 2,000 years ago.
Palestinians have a right to preserve sites particularly given that Palestine was accepted as a full member of UNESCO in 2011, Barghouti said. Russia's minister of culture has agreed to support the application, he added.
PA Tourism Minister Rula Maayeh told Ma'an that adding Bethlehem to the World Heritage list would encourage tourism to the West Bank city and demonstrate its international value.
Russian President Vladimir Putin's visit to Bethlehem on Tuesday helped raise the city's profile and would encourage other visitors, she added.
In Jerusalem, Israeli Foreign Ministry spokesman Yigal Palmor objected to the Palestinian claim that Bethlehem sites are in imminent danger.
"The real purpose here is not really UNESCO support, but simply to bash Israel again," Palmor said. "We have no objection whatsoever to the inclusion of the Nativity Church. The Palestinians are looking for a conflict at any cost."
Nada al-Atrash, of the Bethlehem Centre for Cultural Heritage Preservation, says the bid is urgent as water leaking from the church's roof is damaging icons.
Bethlehem's deputy mayor, George Saade, told reporters Wednesday that the UNESCO bid was intended "to preserve our heritage and most important sites. This city is one of the most important places for Christians. Here God gave us a gift, our beloved Jesus Christ."
He added: "This is not a political issue; it's a civilian issue. It is our heritage ... Israel wants to turn it into a political issue."
Last year, UNESCO granted Palestine full membership, a decision seen at the time as a boost to their bid, since largely stalled, to win unilateral statehood recognition from the United Nations in the absence of peace talks with Israel.
Israel and the United States, which subsequently cut off its $80 million annual funding of UNESCO, condemned the decision, saying peace negotiations - which collapsed in 2010 - were the only path to a Palestinian state