Germany's largest mosque will for the first time broadcast the call to prayer on Friday after city authorities in Cologne gave the go-ahead for a pilot project, under strict limits.

Cologne's Central Mosque, an imposing building in the western city's Ehrenfeld district, will be allowed to send out a single call to prayer over loudspeakers for up to five minutes on Fridays, between noon and 3:00 pm. The volume must not exceed 60 decibels.

The agreement, part of a two-year pilot project, was to be formally be signed by Cologne officials on Thursday.

Mosques in several cities in Germany have long been authorised to broadcast the call to prayer, but Cologne city only approved it from last October.

In majority-Muslim countries, the muezzin calls the faithful to prayer five times a day.

"We're very happy," Abdurrahman Atasoy, general secretary of the Turkish-Islamic Ditib organisation which runs the mosque, told local media.

"The public call to prayer is a sign that Muslims are at home here."

Cologne mayor Henriette Reker said allowing the call to prayer was "a sign of respect" for the city's many Muslims.

But the project has not been without controversy, particularly because of the involvement of Ditib, which has close ties to Turkish President Recep Tayyip Erdogan and manages more than 900 mosques in Germany.

Critics have accused the organisation of spying on Turkish dissidents living in Germany.

Erdogan himself travelled to Cologne in 2018 to inaugurate the Central Mosque, sparking rival rallies by thousands of pro- and anti-government demonstrators.

The Central Mosque, a massive glass and concrete structure designed as a flower bud flanked by two minarets, has room for 1,200 worshippers.

Germany is home to more than five million Muslims, accounting for around six percent of the population.

The city of Cologne, famed for its towering Dom Cathedral, counts more than 100,000 Muslim residents.