Italian police have arrested three asylum-seekers in a terrorism and human-trafficking investigation launched after photos of potential targets in three countries were discovered on suspects' cell phones, prosecutors in the southern city of Bari said Tuesday.

Arrest warrants were issued for two other suspects.

The cell phone data included numerous photos of sensitive sites in Bari, including the airport, port and a shopping mall, as well as sites in Rome, London and Paris, images of weapons and Taliban fighters and audio files of radical Islamic indoctrination.

Prosecutor Roberto Rossi told a news conference that there was no evidence that any attack was imminent "but it is clear they were making preparations."

The phones were seized from four of the suspects after they were detained briefly in December for filming in a shopping mall.

"Just because someone who is Pakistani or Afghan takes pictures does not mean they are dishonest," Rossi said. But he said the prevalence of photos of sensitive sights "where tourists in general don't take pictures ... taken together, they assume an extremely strong meaning."

Hakim Nasiri, 23, from Afghanistan, was arrested in a home for asylum seekers in Bari and was being held on suspicion of subversive association with the goal of international terrorism. Afghan Gulistan Ahmadzai, 29, and Pakistani Zulfiqar Amjad, 24, were detained in Milan on suspicion of aiding illegal immigration. Both had obtained international protection status in Italy.

Rossi said the two still being sought are believed to have returned to their native Afghanistan.