Italy has warned that an influx of Tunisian migrants arriving on its shores could have devastating consequences for all European nations.
Interior Minister Roberto Maroni said migrants who have landed on the island of Lampedusa threaten the institutional and social structures of Europe.
The EU border agency is sending patrol boats and aircraft to assist Italy.
In another development, a boat was intercepted off Sicily carrying about 30 people believed to be from Egypt.
Italian police said the boat was intercepted overnight off the coast near Ragusa.
Meanwhile, in Tunisia, the authorities have lifted a night-time curfew.
But the interior ministry said the state of emergency, which has been in place since President Zine al-Abidine Ben Ali went into exile last month, will continue "until further notice".
Seeking better lives
More than 5,000 immigrants have reached Lampedusa - south of Sicily - by boat in the past week.
The upsurge follows last month's mass protests over unemployment and poverty in Tunisia which resulted in the overthrow of President Ben Ali.
Most of those arriving in Lampedusa say they are seeking work and a better life in Europe, although correspondents say they could include escaped convicts and members of the ousted regime fleeing retribution.
"It is a question that risks igniting an extremely fast process of change in North African countries, that can have devastating consequences on the institutional and social structures of European nations," Mr Maroni said.
"I have asked, and I think it is fundamental, that Europe at its top levels - meaning heads of state and government - defines a strategy... and starts a strong diplomatic action towards all countries that are touched by these phenomena."
Lampedusa Mayor Bernadino Rubeis has declared a state of emergency.
"There is an entire nation trying to escape Tunisia to reach Italy and then to go on to other countries," he said.
The head of EU border agency Frontex, Ilkka Laitinen, said he had accepted an Italian request to help it cope with the wave of immigrants, and would send patrol boats, aircraft and up to 50 personnel.
"The situation is very severe and we are doing our utmost to assist the Italian authorities to cope with this situation," he told reporters at a European police congress.
Laura Boldrini of the UN refugee agency (UNHCR) who is on Lampedusa, told the BBC World Service that the situation on the island was "critical".
She said conditions had improved slightly since the island's reception centre re-opened on Sunday but it was important to move people to other reception centres in Italy.
Ms Boldrini said migrants were either saying they wanted to escape "insecurity" in Tunisia or had left to look for jobs in Europe.
She said some planned to travel on to France and other European countries to be reunited with family members already there.
"This influx is affecting many other countries, not only Italy," she said.
The BBC's Jim Muir in Tunis says many people there are puzzled by the upsurge in the number of people trying to get to Italy, as the situation in Tunisia is seen to be stabilising.
Some of those trying to leave are said to be well-dressed and paying over the odds for the trip, our correspondent says - indicating they might be associated with the former regime and trying to avoid retribution.
But most are believed to be economic migrants taking advantage of a security loophole, he adds.
Michele Cercone, spokesman for the European Commission for Home and Justice affairs, said there had to be a European common approach to increasing migration sparked by recent turmoil in northern Africa.
"On one hand we have to intervene, if needed, with urgent measures to assist member states and on the other hand we have to be sure that we co-operate with... countries of origin of these migrants, in order to have a more consistent and long term solution," he said.
Meanwhile, unconfirmed reports say at least five migrants died and others are missing after their boat sank off the Tunisian coast near Zarzis.
Alleged survivors told AFP news agency that a Tunisian coastguard ship rammed their boat on Friday as it was making its way to Italy.
"The boat... was carrying 120 passengers - 85 people were saved, five died and 30 are still missing," 23-year-old Ziad Ben Abdaalah is reported to have said.
Coastguard officials in Zarzis contacted by AFP confirmed that a boat had sunk but blamed it on the poor condition of the boat and declined to make any further comment.