Palestinian Muslims and Christians have united to renovate a church in Bethlehem on the site that, according to tradition, Mary gave birth to Jesus, the Associated Press reports.

The first stage of the restoration of Bethlehem's Church of the Nativity, built in the fourth century by Saint Helena over the believed site of the virgin birth, has been completed.

"For the first time you can see, when you go up, mosaics really magnificent and beautiful and unique in the whole world," said Ziad al-Bandak, who leads the Palestinian committee in charge of the renovation.

Before the project, the roof was in urgent need of repair, and leaks had ruined a significant number of the church's mosaics and paintings. Now that the roof has been structurally repaired, these treasured art works have been restored to their former beauty.

Due to the tense nature of relations between the three Chrsitian denominations who have stakes in the church – the Catholic, Greek Orthodox and Armenian Churches – renovations had previously been put off. Custom dictates that whoever pays for the renovation of an area of the church would then own it.

According to AP, in 1461, a visitor to the church wrote: "In the roof the timbers which were constructed in ancient times are rotting, and this structure is falling daily into ruin."

This stalemate was overcome through the involvement of the Palestinian authority in 2013, enabling the renovation to be arranged and funded by Palestinian authorities and international donors.

The Palestinian authority's involvement is, in part, motivated by a desire for the church to be recognised as a World Heritage Site by UNESCO.

Al-Bandak sais that nearly $8 million has already been spent and the international team working on the church include Italians who specialise in the renovation of historical sites.

The structural issues with the roof have been resolved and, for the first time in almost a millenium, the thousands of fine mosaic tiles have been retouched, according to AP.

The full restoration is expected to take at least another three years and is predicted to cost a further $11 million, al-Bandak said.

Although they do not have the funds yet, President Mahmoud Abbas told al-Bandak to press on with work. "He told me from the beginning: 'Even if you don't have all the money to go ahead, star. This is a holy place and money will come,'" he said.