President Francois Hollande called on London to help deal with the plight of thousands of people whose dream is ultimately to get to Britain.
At least 600 Egyptian, Syrian and African migrants were aboard the boat.
Organisations had been warning of deplorable conditions and slow-moving asylum claims on Lesbos for months.
It's been dubbed 'The Great Wall Of Calais'.
Some 500 people were saved in three rescue missions on Tuesday.
It's high time we recognised that immigrating to a new country takes courage and resilience. Those who do it are typically far from what you'd call weak or vulnerable -- in contrast, they are most often very strong and deserving of admiration, not pity.
Around one in 10 refugees traveling through Europe is pregnant.
Refugees and migrants continue to attempt a perilous journey to Europe.
By Steve Scherer ROME (Reuters) - A photograph of a drowned migrant baby in the arms of a German rescuer was distributed
The migrants — fleeing wars, oppression and poverty — often do not know how to swim and do not have life jackets.