An EU deal to return rejected asylum seekers from Greece to Turkey is due to begin implementation today.

The Turkish interior minister said the country was prepared for up to 500 migrants in the first transfer. The EU signed the controversial deal with Turkey last month, as it wrestles to contain the continent's worst migration crisis since World War II. Under the agreement, all migrants and refugees who reached the Greek islands after March 20th face being sent back to Turkey.

Germany has sent police and migration officers to Greece to help with the transfers. However, the deal doesn't seem to be deterring migrants from trying to enter the bloc.

The Greek coast guard said more than 360 refugees were rescued over the weekend. The UN refugee agency has warned of possible human rights violations in the transfers. 

"We feel that there's still deficiencies and gaps in both countries that need to be addressed. We're not opposed to returns as long as people are not in need of international protection, they have not applied for asylum and human rights are adhered to," said Boris Cheshirkov, UNHCR Spokesman in Lesbos.