(BRUSSELS) - European nations will send guards to Greece's border with Turkey to help Athens cope with an overwhelming influx of illegal migrants from north Africa and south Asia, an official said Monday.

The European border agency, Frontex, will announce within five days the details of the assistance it will send after Greece sounded an alarm on Sunday, European Commission spokesman Michele Cercone told a news briefing.

Greece became the first EU country to ask for help from the EU's Rapid Border Intervention Teams after hundreds of migrants from north Africa and war zones such as Iraq, Pakistan and Afghanistan flooded through the porous Greek-Turkish border in recent weeks, Cercone said.

"We know that part of the border is currently neither controlled nor guarded. Greek authorities cannot manage to assure control of this part of the external border of the European Union," he said.

It is too early to know which countries will contribute border guards and how many would be deployed, but EU countries are required to meet the Greek request, Cercone said.

The guards from other European nations will be armed but can only use their weapons for self-defence. They will work under Greek orders and will act only in the presence of a Greek official.

The announcement came less than a week after a UN expert said migrants in Greece were frequently held in "inhuman" conditions due to "filthy overcrowded detention facilities," poor police training and a spike in arrivals.

United Nations special rapporteur on torture Manfred Nowak said last Wednesday that urgent measures were needed to restructure the way asylum seekers and migrants are dealt with.

"I appeal to the European Union, and the commission in particular, to assist the government... they are in need of very substantial financial and technical assistance so that the crisis can be solved," Nowak said.

European home affairs commissioner Cecilia Malmstroem said Sunday that the the situation at the Greek-Turkish border was "increasingly worrying" and that the flow of illegal migrants had reached "alarming proportions."

"I am very concerned about the humanitarian situation," she said.

Frontex said more than three-quarters of the 40,977 people intercepted while clandestinely immigrating into the EU in the first half of 2010 entered through Greece, mainly coming from Turkey.