The rescue ship Aquarius, which has picked up almost 3,000 migrants from the Mediterranean this year, will carry out rescue missions without waiting for orders from coast guards and will not return people to Libya, its search and rescue head said.

"When we see there is a vessel in distress, with a high likelihood of people dying, we will go and rescue them immediately as per international maritime law," Nick Romaniuk told Reuters on board the Aquarius.

Over the last year coordination centders asking rescue vessels to go on standby or wait for clarification on certain things had added to the danger of people needing to be rescued, which is why they would no longer wait, he added.