Vessels from five European Union nations have launched sea patrols in an attempt to combat illegal immigration.

The operation, codenamed Ulysses, is aimed at stopping the gangs that bring immigrants on dangerous sea voyages from Africa.

"Today we are surely seeing the birth of a common police force for the European Union to protect our borders," Spanish Interior Minister Angel Acebes said on the Mediterranean island of Mallorca.

The European Commission estimates that there are nearly three million illegal immigrants in the 15-nation EU.

Many are brought by gangs on rickety boats, and bodies are regularly washed up on Spanish and Italian beaches.

A Moroccan immigrants' rights group in Spain, ATIME, estimated last year that about 4,000 people had drowned in the Strait of Gibraltar and in the Atlantic between Africa and the Canary Islands since 1997.

Two phases

Six vessels - two Civil Guard patrol boats from Spain, a customs ship from the UK and navy ships from France, Portugal and Italy - are taking part in the pilot scheme. They will be based at Algeciras, Spain.

The first phase will target the western Mediterranean from Algeciras to Palermo in Sicily. After 8 February, the patrols will be extended to the Canary Islands.

Each ship will be responsible for an area of six square miles (15.5 square kilometres).

The EU wants to secure its maritime borders

They will have the power to board any suspect vessels and escort them to the nearest EU port if necessary.

Observers from Greece, Norway, Germany, Poland and Austria will also take part in the operation.

"This is a project in which, over several days, we are going to test how it is possible to co-ordinate our actions in order to have control over the maritime borders in the Mediterranean," said Mr Acebes.

He said it would be a step towards a European-wide frontier police force and "a common area of security, justice and freedom".

The EU is considering setting up a European corps of border guards to curb the growing number of illegal immigrants.

Tougher measures are being considered to coincide with the EU's proposed expansion eastward that will admit 10 new member states and open new areas for smugglers.