More than 2,500 people have died making the crossing this year, not including about 200 who are feared to have drowned off Libya on Thursday. That compares with 3,500 who died or went missing in the Mediterranean in 2014.
Among the forces driving people to take such risks are the conflicts raging in Syria and Afghanistan, and human rights abuses in Eritrea. The majority - 62% - of those who have reached Europe by boat so far this year are from those three countries.
There are also people setting out from Libya, Sudan, Pakistan, Nigeria, Kosovo, Iraq, Iran Darfur, Somalia and other countries in the hope of a new life somewhere like Germany, France or the UK.
People fleeing Syria had long sought refuge in neighboring countries, hoping to return home, but were increasingly opting to head straight for Europe, a choice compounded by tighter entry rules imposed by Syria's neighbors, which already have huge refugee populations.
Other big refugee-hosting countries, which include Jordan, Turkey and Iraq, were "just over-full with refugees, and they are receiving far too little support from us because we're underfunded", Fleming said.
The dangers of the sea route across the Mediterranean have been highlighted by the ever growing death toll. A Red Crescent official said on Friday Libya had recovered 82 bodies washed ashore after a boat packed with migrants sank near the western town of Zuwara.
On Thursday, 51 people suffocated in the hold of a boat. Survivors said smugglers had beaten them to force them into the hold and extorted money from anyone wanting to come out of the hold to breathe, Fleming said.
One survivor, an Iraqi orthopedic surgeon, said he paid 3,000 euros ($3,385) to come up onto the top deck with his wife and two-year-old son.
The European search and rescue operation FRONTEX had saved tens of thousands of lives this year, but EU countries must do more to act together to deal with the problem, which UNHCR has repeatedly said would be manageable with the right action.
