LLAUSHE, Kosovo (AP) — The father of a Kosovo man arrested in Italy on suspicion of plotting to bomb a bridge in Venice says he is convinced that his son "has not planned or organized any terrorist attack."

Arjan Babaj is one of three Kosovars arrested Thursday in the case. One allegedly was caught on a phone intercept proposing a bomb attack on Venice's famed Rialto bridge. A minor was also detained.

The four suspects worked as waiters at tourist restaurants in Venice and frequented a Venice mosque. No explosives, weapons or bomb-making materials were found in the apartments searched but police say they did find videos of Islamic extremists demonstrating how to carry out knife attacks.

The suspects allegedly posted inflammatory Islamic State videos on Instagram and Facebook accounts using fake names, with recent posts exulting jihads as triumphant martyrs. The accounts had some 18,000 followers, Italian newspaper La Repubblica said.

Bedri Babaj told The Associated Press on Friday that he believes his son is innocent. He argued there are few practicing Muslims in Venice and that this may have aroused suspicions.

"I am fully convinced nothing is true," he said, speaking from his villa in Llaushe, 60 kilometers (37 miles) west of the capital, Pristina.

Babaj said his son had been intensively practicing Islam in the last four or five years, also persuading some friends to do the same.

In an interview Friday, Venice prosecutor Adelchi d'Ippolito said the suspects were getting into shape in a "meticulous, careful and rigorous way."

"They were very concerned about their bodies and working out to get into shape. They watched films of aggressive techniques, and using knives and how they can inflict wounds," he said.

A few hundred Kosovars are believed to have joined Islamic extremist groups in Syria and Iraq in recent years. Kosovo authorities say about 70 are still active with extremist groups there.

Llazar Semini in Tirana, Albania and Nicole Winfield in Rome, Italy contributed.