Nearly 12,000 immigrants were arrested entering Greece illegally last month - an almost seven-fold increase from the previous year, the country's coast guard has said.
The agency said 11,873 people were arrested in April and 6,583 were arrested in March - nearly all on islands facing the coast of Turkey.
EU migration commissioner Dimitris Avramopoulos, on a visit to Athens yesterday, said he would back a European Union relocation plan to assist Greece and Italy.
Greece's government has welcomed the plan but is seeking a higher quota, to help it cope with large numbers of migrants arriving from war-torn Syria.
According to government estimates, some 37,500 immigrants and asylum seekers have reached Greece illegally so far this year.