A boat loaded with migrants reaches the Sicilian island of Lampedusa, Italy, in early March. Associated Press.

Italy is facing a humanitarian and sanitation crisis on the tiny island of Lampedusa following the arrival of some 15,000 Tunisian boat people amid fears more migrants will flee there following coalition airstrikes on Libya, the United Nations warned Monday.

Lampedusa is currently housing some 4,800 Tunisians, almost doubling the island's population of 5,000 and putting a severe strain on its immigrant holding centre, which has a capacity of just 850.

Italy had been ferrying and airlifting the migrants off the island to be processed at holding centres elsewhere. But those centres are now full, leading to a backlog in Lampedusa — the primary point of arrival for North Africans due to its close proximity to Africa.

The United Nations refugee agency warned in a statement that some 3,000 of the migrants have been forced to sleep outdoors, "either next to the centre or on the docks, without any protection from the rain in increasingly critical hygienic conditions."

Italian Interior Minister Roberto Maroni said measures would be taken in coming days to stem the flow and ease the burden on Lampedusa, including a visit to Tunis Wednesday to press for a resumption of the immigration treaty agreements and border controls that evaporated after the country's popular revolt in January.

He pointed out that only 25 Tunisians had arrived in Lampedusa in 2010, but so far, "14,000 have arrived in two months."

Maroni said an Italian navy ship would be sent to the island to transport migrants to holding centres elsewhere in Italy, and he would be meeting with regional officials to find additional centres.

Maroni also announced compensation measures for the island, whose economy is driven by tourism, as fears mount among residents that the crisis will ruin the approaching high tourist season.

Maroni told a news conference Monday that some 200 Libyans from the country's east had arrived overnight in Catania, Sicily, marking the first major influx from Libya to Italy since the revolt against Moammar Gadhafi began over a month ago.

But it appeared his information was outdated. Officials from Catania's port, police, carabinieri and financial police said the migrants were Egyptians, not Libyans — news reports indicating they claimed to be Libyans to obtain refugee status.

Italy has been sending back the vast majority of the 14,918 Tunisians and Egyptians who have arrived at its borders in recent weeks following popular revolts in their home countries, saying they don't qualify for asylum or refugee status as there are no wars or humanitarian crises in their countries.