UNHCR spokesperson Ron Redmond told reporters in Geneva that the average number of people arrested, intercepted or rescued by Greek coastguard officials has been about 3,000 each year since 2002, but already this year there have been nearly 4,500 cases.

He noted that Greek police are reporting even higher arrest figures from just three islands: Samos, Chios and Lesvos, which are all close to the coast of neighbouring Turkey.

The surge in arrivals has led to overcrowding in the detention centres in Samos, Chios and Lesvos, Mr. Redmond said, after that a holding centre in Samos sparked particular concern because of lowered hygiene standards. UNHCR has called for that centre’s immediate closure.

“We welcome the announcement by the Interior Ministry of Greece that all persons currently in the old centre will be transferred to a newly-built centre in Samos which will open at the end of this month,” he said.

Many of the arrivals are Iraqis, Afghans and Somalis, as well as migrants from other countries in the Middle East, the Horn of Africa and South Asia. Some 3,500 Iraqis applied for asylum in Greece in the first six months of the year, the second highest number of any industrialized nation after Sweden, although this figure includes arrivals by land and air as well as by sea.

Mr. Redmond added that the surge in arrivals in Greece coincides with a sharp drop in the number of irregular arrivals by sea into Italy and Spain. In the case of the Canary Islands, which are part of Spain, the numbers have slumped by as much as 60 per cent this year.