The two-week operation will "apprehend irregular migrants" and is aimed at "weakening the capacity of organised crime groups to facilitate illegal immigration to the EU", according to a European Union document.

Migrants found without papers will be sent back to their country of origin if it has signed a repatriation agreement with the EU, be placed in a detention centre or released with an expulsion warning.

All 26 countries in Europe's visa-free Schengen area -- which groups 22 EU members as well as Norway, Switzerland, Liechtenstein and Iceland -- were invited to take part, with only one declining, a European source said, declining to name the country.

The operation is dubbed "Mos Maiorum" -- the Latin for "laws of the elders", or the ancestral customs of the ancient Romans -- and is the latest in a series of such exercises held every six months.

Rights groups criticised the launch of the operation, which comes as Europe faces a rise in the number of migrants fleeing troublespots in the Middle East and North Africa.

Campaign group Frontexit said it was "yet another battle in the war the EU has waged against an imaginary enemy."

A record figure of more than 3,000 migrants have died trying to cross the Mediterranean this year, the International Organisation for Migration said Monday, while Amnesty International last month said a "Fortress Europe" mentality was fuelling the business of smugglers and putting lives at risk.

The EU is to launch a new sea mission to save migrants in the Mediterranean next month dubbed "Triton".

Global Post/AFP