Image result for Rotterdam, Dutch police

Rotterdam police have arrested a Dutchman found with a loaded AK-47 Kalashnikov and illegal fireworks who is "suspected of preparing a terrorist crime," prosecutors said Friday.

The 30-year-old was detained on Wednesday after police raided his apartment following a tip-off from the Dutch intelligence services.

Police found the gun, two loaded magazines and four boxes of illegal fireworks during the raid, prosecution spokesman Wim de Bruin told AFP.

"He's suspected of preparing such a terrorism crime, but we don't have information about the specific details," De Bruin told AFP.

The man has been taken into custody for questioning and is due to appear in court in two weeks.

Police also seized a painting with a picture of the flag used by the so-called Islamic State, mobile phones and some 1,600 euros ($1,686) in cash.

Rotterdam is Europe's busiest port, and also one of The Netherlands most multi-cultural societies, home to many who have emigrated from abroad.

Dutch law enforcement agencies have been on high alert across the country since the November 2015 bombings in Paris, and the March suicide attacks on the Brussels metro and airport. Both France and Belgium neighbour the small northern European country.

Last week, the European police agency Europol warned that terror networks such as Islamic State are evolving their tactics to attack soft targets across the continent.

And the Dutch counter-terrorism agency has warned that fighters who left to join IS in Iraq and Syria could pose a threat as they return home.

About 270 Dutch people left to join the jihadists, and about 40 former fighters are known to have returned from combat in Syria and Iraq, where most have been fighting against Syrian President Bashar al-Assad's regime.

Another 190 Dutch citizens including women and children are still in Syria and Iraq, the agency said in a report last month while 44 fighters have been killed.

"The number of returning jihadist fighters will pick up should the 'caliphate' be militarily defeated or collapse," the agency said in its latest "Terrorism Threat Assessment".

"An increased number of returnees will most likely strengthen the jihadist movement within The Netherlands and therefore increase the threat posed by this group," it said.