Five "key organisers" of an Italian-based group accused of trafficking drugs and humans to finance Islamic terrorism have been arrested in Italy, the UK and France, an EU justice body said Wednesday.

Two suspects were arrested Tuesday in Italy, two in the United Kingdom and one in France, Eurojust said in a statement, adding that house searches were still ongoing in a probe that started in 2007.

"The group had its headquarters in Rome and Milan and was involved in illegal immigration and drug trafficking for the purpose of financing Islamist terrorism," it said.

"The group trafficked Afghan and Pakistani nationals with counterfeit documentation via Iran, Turkey and Greece to Italy. After arrival in Italy, the victims were put in trucks bound for Germany, Sweden, Belgium, the UK and Norway."

In a related operation, French authorities arrested six other members of the same organisation a few days ago, said Eurojust.