Dramatic images released by the Italian navy show the moment a heavily overcrowded boat overturned off Libya, leaving at least five people dead.

The blue fishing vessel, its deck heaving with people, tipped over after the migrants rushed to one side on spotting a rescue ship — an all too frequent mistake which has led to many disasters in the Mediterranean.

Hundreds are thrown into the water as the boat capsizes. ( AFP: Marine Militare/STR )

The migrants had sounded the alarm by calling for help using a satellite phone about 18 nautical miles off Libya.

The navy said its patrol boat, Bettica, then spotted "a boat in precarious conditions off the coast of Libya with numerous migrants aboard".

The trawler overturned shortly afterwards "due to overcrowding".

Sorry, this video has expired The navy was quick to respond to pull 562 people to safety

Survivors swam towards the Bettica as the rescue vessel's helicopter whirred overhead. The navy said 562 people were pulled to safety.

The overturned boat after its capsize. ( AFP: Marina Militare/STR )

The operation wound up late on Wednesday without finding any further survivors or victims.

The Bettica went on to pluck another 108 migrants from their dilapidated vessel in a second rescue operation.

The navy rushes to rescue passengers. ( AFP: Marina Militare/STR )

AFP