The blast occurred at the intersection of Aleja Bologna and Gospodska streets near the rail tracks where another explosion happened two days before, damaging the rail tracks and a cargo train that hit an explosive device.

Media reported that the 53-year-old man, who was injured in the latest explosion, was suspected of planting both explosive devices, but the police said it was too early to make such conclusions.

The Zagreb chief of police Goran Burusic said that it had not yet been established how the injured man had happened to be on the site of the second explosion and that it was too early to comment on his status.

Criminal Police Commissioner Vitomir Bijelic told Croatian Radio on Friday morning that police and the State Prosecutor's Office for now believe that there were no elements in last night's explosion or in the explosion that took place in the same part of the city early on Wednesday morning, that could qualify the two incidents as acts of terrorism and for now the explosions were treated as acts against public security.

"The material evidence, including the remains of the explosive device, will be analysed, and after that it may be possible to say whether the two explosions are connected either by the same perpetrator or by the same type of the explosive device," police spokeswoman Jelena Bikic told the media.

The police also dismissed the speculations that in the night between Thursday and Friday there had been more detonations in west Zagreb, as reported by media, or that the police had found more explosive devices in the area.

Following the explosion near the Podsused railway station at 0350 hours on Wednesday, the police questioned more than a hundred people, but none was declared a suspect.

After the two explosions, railway traffic on this part of the railway network, which is part of the pan-European Corridor X, was suspended for several hours.