ROME (AFP) - A video of a group of migrants being washed down in a centre on the Italian island of Lampedusa has caused a wave of outrage in Rome and Brussels, less than three months after a shipwreck in which hundreds died.

The male migrants - some of them naked - are shown queuing up to be disinfected after being checked by nurses in what appears to be an open space at the centre in footage shown by Rai 2 state television.

The EU's Home Affairs Commissioner Cecilia Malmstroem on Wednesday condemned "appalling conditions" at some of the migrant centres in Italy including Lampedusa and said an EU investigation was already under way.

"The EU is committed to assist Italy in receiving migrants, but it has to be done in decent conditions," Malmstroem said on Twitter, adding: "We will not hesitate to launch an infringement procedure to make sure EU standards and obligations are fully respected."

After Lampedusa's mayor Giusi Nicolini said the images were reminiscent of "a concentration camp", Italian Prime Minister Enrico Letta promised to investigate and to punish anyone held responsible.

The United Nations refugee agency UNHCR in a statement joined the chorus of outrage, which coincides with the UN's International Migrants Day.

"The constant overcrowding that occurs is unsustainable and leads to a situation where, despite the efforts of humanitarian workers, the assistance offered is far below the minimum standards," spokesman Laurens Jolles said.

But Cono Galipo, the head of the contractor that runs the Lampedusa centre on behalf of the interior ministry, rejected the accusations.

Galipo said in a radio interview that the migrants seen lining up naked had in fact stripped down because they were "impatient" as they awaited their disinfection shower and had "clearly staged the images seen".

"It should all be contextualised. We had just had three landings in which the risk of scabies was very high.

"Usually when there are a few people we do the treatment in the clinic but there were 104 people and there was no other space free," he said.

Tens of thousands of migrants land in Italy every year, paying sometimes thousands of euros each to smugglers who ship them from the shores of Egypt, Libya or Turkey on rickety and badly overcrowded boats.

Italy complains it has to shoulder an unfair burden as one of the main points of entry for migrants into Europe, although countries in northern Europe point out that they resettle a far higher share of refugees.

Many of the migrants transit through Lampedusa, a tiny island that is closer to the Tunisian coast than to the rest of Italy and has turned into a major gateway for irregular migration into the European Union.

The latest figures show 14,000 migrants have transited through Lampedusa so far this year.

The island's 381-bed facility is often too full and many migrants have been forced to stay in unsanitary conditions and sleep out in the open, awaiting transfer to other migrant centres in the rest of Italy.

The rocky outcrop hit the headlines in October when a boat laden with migrants - mainly from Eritrea - caught fire and capsized within sight of the shore as they were trying to signal to Italian coast guards.

The shipwreck claimed 366 lives in the worst ever Mediterranean migrant tragedy, prompting calls for an overhaul of European immigration and asylum policies.

The European Union has published a list of proposals aimed at avoiding a repeat of the tragedy which are to be put to an EU leaders' summit on Dec 19 and 20.

They include beefing up border surveillance, boosting EU assistance to member states facing the biggest influx of migrants, improving the fight against human trafficking and opening more legal channels to reach Europe - including resettling more refugees in the EU.

Immigration charities say it is now time to act after multiple tragedies at sea over the past 20 years in which between 17,000 and 20,000 migrants have perished.

But tackling the problem is tricky at a time when Europe is in economic stagnation and when governments fear that appearing to facilitate migration could cause a backlash among their crisis-hit populations.