Countries in southern Europe have urged the rest of the EU to share the burden of accepting migrants from North Africa as a new influx is predicted.
Italy, Spain, France, Cyprus, Malta and Greece presented joint proposals at a meeting of EU interior ministers in Brussels on Thursday.
The six countries want a common EU asylum system to be in place in 2012.
But Italian warnings of a "Biblical" exodus from Libya were given a cool reception by Germany and others.
The BBC's Chris Morris in Brussels says at least one million migrants, many of them from sub-Saharan Africa, are believed to be in Libya, hoping to reach Europe.
Many of them may be political refugees, not simply economic migrants, so Europe has an obligation under human rights agreements to identify genuine refugees who have a right to asylum.
The UN High Commissioner for Refugees, Antonio Guterres, appealed to the EU to help the Libyan people.
"If the situation gets even more dramatic, if we move into a level of fighting that forces a massive outflow from Libya, it's very important that protection space is guaranteed in Europe," he said after meeting top EU officials.
The six Mediterranean countries whose ministers met in Rome on Wednesday demanded a programme for relocation - that is, spreading asylum seekers around Europe if they arrive in large numbers.
They want a special solidarity fund to be set up to help them process arriving migrants.
"We are in front of a humanitarian emergency and I ask Europe to settle all the necessary measures to deal with a catastrophic humanitarian emergency," Italian Interior Minister Roberto Maroni said in Brussels on Thursday.
Spanish Interior Minister Alfredo Perez Rubalcaba backed up his counterpart, saying Italy was "only the door of Europe".
Our correspondent says these are extremely controversial proposals, which will not be warmly received by Britain or many other countries.
Austrian Interior Minister Maria Theresia Fekter said her country had received hundreds of thousands of refugees during the Balkan wars in the 1990s, and Italy was capable of handling on its own the 5,000 illegal migrants from Tunisia who arrived last week on the island of Lampedusa.
Germany's Interior Minister, Thomas de Maiziere, said there was "no refugee influx right now" and states should not "provoke one by talking about it".
"Let's not play at scaring ourselves," said Belgium's Melchior Wathelet.
In a recent ruling, the European Court of Human Rights challenged the EU's Dublin II Regulation, under which asylum seekers are sent back to their point of entry into the EU.
The regulation is intended to prevent "asylum shopping" in Europe, but it has exacerbated the dilemma of Greece, which is struggling to cope with thousands of asylum applications.
Lampedusa - a tiny island in the Mediterranean between Tunisia and Italy - is a major entry point to Europe for immigrants from Africa.
In recent years Malta and Spain have also intercepted numerous boatloads of migrants from Africa. Often the boats are rickety and migrants risk their lives in their desperation to reach Europe.
The EU border agency Frontex is providing Italy with logistical support.
As the uprising in Libya intensified, the government of Col Muammar Gaddafi warned the EU that it would stop co-operating on illegal migration from North Africa if the EU backed those seeking to topple him from power.
In recent years, Italy and Libya have co-operated to intercept boatloads of illegal migrants in the Mediterranean. The number of such boats fell sharply after the systematic interceptions began.