The bodies of 21 women and one man were found on a rubber dinghy adrift near the Libyan coast on Wednesday, just hours after they had set sail for Italy, humanitarian group Medecins Sans Frontieres said.

An MSF ship patrolling the central Mediterranean came to the rescue of two dinghies that were sailing close together and managed to pull 209 people, including 50 children, to safety.

However, 22 refugees were found dead at the bottom of the first dinghy, lying in a pool of fuel.

"It is still not entirely clear what happened, but they died a horrible death. It is tragic," said Jens Pagotto, MSF Head of Mission for Search and Rescue Operations.

"It seems that water and fuel mixed together and the fumes from this might have been enough for them to lose consciousness," he told Reuters.

The survivors, most of them from West African states such as Nigeria and Guinea, were being brought to Sicily along with the dead and were due to reach the port of Trapani on Friday.

Italian authorities have reported a jump in the number of migrants who have left Libya this week on overcrowded boats in search of a better life in Europe, as people smugglers take advantage of calm seas and hot summer weather.

Oxfam revealed in a report released Monday that the six wealthiest nations host less than 9 percent of the world’s refugees.

More than 2,500 people were rescued Tuesday and one body was recovered, Italy's coast guard said. Almost 600 people were saved on Wednesday.

As of Monday, 79,861 migrants had arrived in Italy by sea so far in 2016. compared with 83,119 during the same period last year. Almost 3,000 migrants have died or gone missing in the Mediterranean this year according to the International Organization for Migration.

"The survivors had been on the boat with the bodies of these women for hours on end. Many are too traumatized from what they have endured to be able to talk about what had happened," said Pagotto.