Berlin (CNN)Six Syrian nationals detained in raids by German police were released without charge Wednesday after initial investigations found there wasn't "sufficient evidence of a terror plot," the Frankfurt prosecutor's office said.
Suspects held in supposed German Christmas market plot released
There was also "no concrete evidence" the suspects belonged to the ISIS terror group, the office said.
There are, however, indications the men have had contacts with ISIS and investigations are ongoing, the office's Christian Hartwig said.
A German intelligence officer previous told CNN that the arrest of the Syrians uncovered a possible terror plot on a Christmas market in Germany.
The men were detained following large-scale raids in four cities involving approximately 500 officers on Tuesday morning led by the Hessian State Criminal Police and the attorney general of Frankfurt, a joint statement by the two agencies said.
The men were targets of an investigation "into suspicion of membership in a terrorist organization and for preparation of terror attack," the original statement said.
According to the initial account from police, the Syrian nationals had applied for asylum and were suspected of being ISIS members. An attack "had not been fully planned yet" according to the previous statement, but the suspects were believed to have been planning to carry out attacks with "weapons or bombs on a public target in Germany."
The German intelligence official, who spoke on condition of anonymity, further claimed the suspects had been carrying out target reconnaissance of the areas in which Christmas markets in Essen, Germany, would be held. They'd also surveilled buildings in Berlin, the official alleged.