The Dutch authorities have released five of seven people arrested on Thursday on suspicion of planning to bomb a popular Amsterdam shopping area, BBC reported.
Among those to have been freed was the sister of a militant Islamist involved in the 2004 Madrid train bombings.
Of two people, both Moroccan men, still in custody, only one is being detained on suspicion of terrorism offences.
The anonymous warning which sparked the arrests prompted the closure of a major shopping street in the city.
The police also postponed a concert by the American band, The Killers, after receiving the warning on Wednesday from a caller in Belgium.
On Friday afternoon, officials appeared to cast doubt as to the credibility of the warning. Although they said the investigation into the threat was continuing, they released five people without charge.
Prosecutors said one of the two Moroccan men still being held was "being interviewed for offenses other than terrorist activities", and that stolen goods had been found during a search of his home.
Amsterdam Mayor Job Cohen said no explosives had been found during searches of buildings linked to the suspects, and that no serious threat remained.
On Thursday, Mr Cohen said the anonymous call to police had not been a "regular bomb warning, but a warning of a planned action".
"Men were planning to put explosives in the shops and wanted to cause casualties in busy places," he added.
The authorities "couldn't take any risks", he said, and so had ordered the closure of dozens of shops, including an outlet of Ikea.
The shopping area that was sealed off was given the all-clear to re-open on Friday, although police maintained a strong presence.
Prime Minister Jan Peter Balkenende said the warning showed "that we must remain alert for threats to our security".