Parts of Nigeria's biggest city, Lagos, have been turned into an "open-air gallery", in the words of the organisers of the city's first street art festival.

"We believe art shouldn't be confined to galleries and museums," Osa Okunkpolor, a Nigerian graffiti artist known as Osa Seven, and one of the festival's founders, told Reuters news agency.

"Public art allows people to interact with creativity in their everyday environment. It's about giving hope and showing what art can do to shape society."

The artwork is on display on Ozumba Mbadiwe Avenue, a busy street in Victoria Island in the heart of the city.

Although Lagos is known for its vibrant arts scene, nightlife and creativity, street art is relatively unknown.