People traffickers deliberately wrecked a boat that sank in the Mediterranean with 500 migrants feared dead, survivors have claimed.

Two survivors plucked from the water by a freight ship have said the criminals rammed their boat after they refused to switch to a vessel they feared was too small to hold them.

Dozens of Gazans are suspected to be among those who may have died last week, a Palestinian official has revealed.

The Palestinian survivors told the International Organisation for Migration (IOM) that around 500 passengers had been on the stricken vessel, which set off from Egypt bound for Europe on September 6th.

The passengers, who also included Egyptians, Sudanese and Syrians, were forced to change boats several times during the crossing towards Europe, they said.

The IOM described the sinking as the "worst shipwreck in years," and said that if the survivors' claim was true it would amount to "mass murder".

Fayez Abu Eita, a Gaza spokesman for president Mahmoud Abbas' Fatah party, said: "We have information that 15 (Palestinians) drowned and dozens more are missing after trying to emigrate to Italy.

"The severe living and humanitarian conditions of the Palestinians are forcing people to emigrate."

A relative said 15 members of a single family were among the missing.

The relative told the AFP news agency: "Fifteen people from the Masri family, including two brothers, a woman and two of her children, left to emigrate to a European country through a broker, and got on a boat from Alexandria headed for Italy.

"We've no news of them, whether they've drowned or survived."