World's largest marine reserve created off Hawaii

US President Barack Obama has expanded a national monument off Hawaii, creating the world's largest marine reserve, the White House says.

His announcement on Friday quadruples in size a monument originally created by President George W Bush in 2006.

The Papahanaumokuakea Marine National Monument will now span 1.5m sq km (582,578 sq miles), more than twice the size of Texas.

The designation bans commercial fishing and any new mining.

The White House says the expansion is helping to protect more than 7,000 species and improves an ecosystem affected by ocean acidification and warming.