The first refugees left Greece on Wednesday under an EU relocation plan, but Prime Minister Alexis Tsipras warned they were a “drop in the ocean” as the number of illegal migrant entries surged to 8,00,000 in 2015.

The six Syrian and Iraqi families, who are starting new lives in Luxembourg, are the first to be relocated from Greece under plans to share out nearly 1,60,000 migrants across the bloc in a scheme fiercely opposed by some EU members.

Mr Tsipras, who was at Athens airport to see the 30 refugees off, said they were making “a trip to hope”.

He spoke as Fabrice Leg-geri, the head of the EU’s Frontex border agency, told Germany’s Bild new-spaper that migrants have made some 8,00,000 “illegal entries” to the bloc so far in 2015 and warned that the influx has probably not “reached its peak”. The need for a solution to Europe’s worst migration crisis since World War II is becoming increasingly urgent as four more migrants, including two children, drowned after their boat got into difficulty off the Greek island of Lesbos on Tuesday.

Meanwhile, Sweden is to ask Brussels to relocate to other EU countries some of the asylum-seekers it has taken in as it struggles with a huge influx, the premier said on Wednesday.

“Sweden has taken a disproportionately large responsibility in comparison with other countries in the EU, and now we are extremely strained,” Prime Minister Stefan Lofven said. “It is time that other countries take responsibility and that is why the government requires redistribution of refugees from Sweden.”

In Germany, defence minister Ursula von der Leyen announced that more than 6,000 soldiers have been mobilised to manage the influx into a country that is expected to take in up to a million asylum-seekers in 2015. This is more German troops than are deployed abroad.