ROME (Reuters) - Italian police on Friday arrested eight people on suspicion of people smuggling and falsifying documents, saying that the gang’s leader had sworn loyalty to Islamic State.

The group of eight, made up exclusively of non-Italians, used fake contracts and payslips provided by a complicit textile company north of Naples to obtain work visas for irregular migrants, Carabinieri police said in a statement.

Heading up the alleged criminal gang was 41-year-old Mohamed Kamel Khemiri, a Tunisian man who had previously been arrested on drug smuggling charges. Khemiri had become a radical Islamist and is under investigation on terrorism charges, police said.

“As long as I live I will be an Islamic State man, and if I die I call on you to join,” Khemiri said, speaking Arabic, on a telephone call recorded by police in January 2015, prosecutor Luigi Alberto Cannavale told reporters.

Khemiri became more and more radicalised over time, investigators said after scouring his internet and social media activity.

He celebrated when militants, who later were said to have acted on behalf of Islamic State (IS), conducted a series of planned attacks in Paris in November that killed 130 people, police said.

“This investigation demonstrates that there is a risk that people close to jihadists can also control people smuggling operations,” Franco Roberti, Italy’s top anti-terrorism prosecutor, told AGI news agency.

On Wednesday, Italy said it is investigating whether IS is involved in organizing the passage of tens of thousands of migrants across the Mediterranean Sea.

More than 420,000 migrants have reached Italy by sea from North Africa since the start of 2014.