President Recep Tayyip Erdogan oversaw a ceremony on Friday inaugurating the £2.3 billion Yavuz Sultan Selim Bridge, which is described by its Turkish-Italian developers as the world's broadest suspension bridge at 58.4 metres wide.

The toll bridge, spanning 1,408 metres over the Bosphorus, features 10 lanes, including two rail lines. At 322 metres, officials say the bridge's towers are also the tallest in the world.

It becomes Istanbul's third bridge spanning the strategic strait.

"This bridge upon which we look with pride will hopefully be a pioneer for many things. We will be proud of it, you will see. International movies will be filmed here, you will see," Erdogan told the audience, among them the king of Bahrain, dignitaries from several other countries and hundreds of citizens.

Some vehicles were permitted to cross the bridge for the first time on Friday, while the general public can start using it Saturday, Erdogan said.

Located near the Black Sea coast north of Istanbul, the bridge is expected to ease traffic gridlock in the city of 15 million, in part because heavy lorries will be required to use it rather than the two older bridges nearer the city.

Not everybody likes the bridge's name. It honours a 16th century Ottoman sultan, Selim, whom the Alevi religious minority blames for instigating a massacre of their people five centuries ago.

Environmental groups have criticised the destruction of forests to build approach roads to the bridge.

The bridge forms part of the 257-kilometre North Marmara Highway, which is scheduled to be completed by the end of 2018.