The British government says it plans to extend a ban on bottom trawling to protect marine life amid calls from naturalist David Attenborough and Prince William for urgent measures to protect the world's oceans.

The plan, which will be subject to a consultation with those in the marine and fisheries sector, would see bottom trawling - dragging large nets along the sea floor - banned across about 30,000 square km (11,600 square miles) of English seas covering 41 Marine Protected Areas, the government said.

It said the move would protect vital marine habitats and support species such as lobster, clams, soft corals and langoustines. Currently there is a ban covering about 18,000 square km of English seabeds.

"Bottom trawling is damaging our precious marine wildlife and habitats," Environment Minister Steve Reed said in a statement.

"Without urgent action, our oceans will be irreversibly destroyed."

The proposal coincides with the start of this week's United Nations Ocean Conference in France, which is seeking to get agreement for a treaty to protect the world's oceans and seabeds from overfishing and other human activities.

On Sunday Prince William, the elder son of King Charles and heir to the throne, called on politicians and business leaders at an event in Monaco ahead of the UN conference to act "while we still have the chance".

Meanwhile Attenborough said he was appalled by what people had done to "the deep ocean floor", saying it was "unspeakably awful".

"If you did anything remotely like it on land, everybody would be up in arms," Attenborough told William in an interview which was released by the prince's office on Saturday.