Christians gathered in southwest Turkey on Saturday to celebrate the birth two millennia ago of Saint Paul, and Catholics hope the event will boost religious freedom in the secular but mostly Muslim state.

Saint Paul, the great evangeliser of the early Christian Church, was born in Tarsus in modern day Turkey and Pope Benedict has proclaimed 12 months of events to honour him.

Hundreds of thousands of pilgrims from Europe and North America are expected to attend the year's celebrations.

Government officials were due to attend Saturday's inaugural ceremonies, although the official start of the Year of Saint Paul is June 29.

Catholics hope the Turkish government will return the St Paul church in Tarsus, which was confiscated by the state in 1943, to Christian worshippers.

Although pilgrims and local Catholics can worship for free in the building after their applications are approved by local authorities, the place is used daily as a museum.

It has bare walls and no cross and the museum entry fee is two lira ($1.6) for visitors.

"We are waiting for the government to fulfil its promise to allow us to be able to pray in a church, not a museum," Bishop Luigi Padovese, apostolic administrator for Anatolia, told Reuters.

Turkey, which is more than 99 percent Muslim, is officially secular, and religion is tightly controlled by the government. Other non-Muslim religious communities have urged the government for greater freedom to practise their faith.

There is no other church in Tarsus for pilgrims or the 100 Turkish Catholics who live in the area.

Prime Minister Tayyip Erdogan, who says he champions religious tolerance, previously said he would support the project to restore the museum to a church in exchange for greater freedom for Turks living in Germany to build mosques.

But Erdogan, whose party is facing closure for alleged Islamist activities, is not expected to attend the celebrations as Bishop Padovese and other Catholics had hoped. And Turkey's non-Muslim communities say the government is still not doing enough.

Contentious issues about religious freedom still loom, such as the opening of a Greek Orthodox theological school near Istanbul and greater rights for Alevis, who practise a kind of Islam steeped in Shamanist traditions.

Still Catholics believe the government will deliver.

"The Turkish authorities have been open to our request and we still have faith the church will be opened," Bishop Padovese said.