Some 200,000 seafarers are affected, with COVID-19 travel restrictions make it almost impossible to rotate crews, according to the UN's International Maritime Organization. Many have been at sea for longer than an 11-month limit laid out in a maritime labor convention

Shipping industry officials say many sailors are at breaking point, in a situation the United Nations has described as a "humanitarian crisis". Maritime welfare charities have warned of an increase in suicides.

In a virtual summit hosted by Britain, representatives of Denmark, Germany, Greece, Indonesia, the Netherlands, Norway, the Philippines, Saudi Arabia, Singapore, the United Arab Emirates and the United States agreed to open up foreign borders for seafarers and increase the number of commercial flights to speed up repatriation efforts, a UK government statement said.

They also committed to designate seafarers as "key workers" and encouraged other countries to follow.

"Today marks a new chapter for seafarers and, alongside our international partners, we are taking a stand to end the bureaucracy preventing men and women around the world from returning home," Britain's Transport Secretary Grant Shapps said.

About 90% of world trade is transported by sea, and coronavirus restrictions in some jurisdictions are still affecting supply chains despite an easing of lockdown in many parts of the world.

Guy Platten, Secretary-General of the International Chamber of Shipping association, said the countries who had agreed to open up borders must now act on their commitments.

"Governments must now use this summit as a catalyst to implement the solutions the shipping industry has provided, applying the political will needed to put them into practice," he added.