Polish police said on Tuesday they had not established terrorist links with three Pakistan nationals and a Ukrainian who were arrested on Sunday amid fears of a terrorist attack on Polish soil.
Police spokesman Dariusz Nowak was quoted by the PAP news agency as saying the suspects would be freed.
Suspicions were aroused after police found a map of Warsaw, with its synagogue and the British and Czech embassies and police headquarters marked in the apartment occupied by two of the Pakistani nationals.
The Polish office of immigration, which is next door to the Czech embassy, said the people in question were legally residing in Poland and had requested refugee status.
"The marked places concerned offices which were linked to the immigration formalities, as was the documentation, in English and Arabic, linked to their stay in Poland." Nowak said. "The marks were not precise".