Both men were arrested as part of the investigation into the person or persons who ordered the murder of De Vries, who was shot at point-blank range in a busy Amsterdam street on July 6 last year . The campaign reporter died nine days later at the age of 64.
Prosecutors gave no details about the identities of the new suspects or their alleged roles in the murder.
On Monday, prosecutors announced they had arrested a 27-year-old Pole suspected of masterminding the hit.
Two other suspects – the alleged shooter and the fugitive driver – were tried in Amsterdam for murder. The judges are due to deliver their verdict on July 14. Prosecutors have requested life sentences for both men.
De Vries made a name for himself as a crime reporter. Later in his career, he campaigned tirelessly to solve cold cases. Prior to his shooting, De Vries had served as an adviser and confidant to a witness in the trial of the alleged leader and other members of a criminal gang that police described as an “oiled-up killing machine”. The witness’s brother and his lawyer were both murdered.
Last month, prosecutors urged judges to find suspected gang leader Ridouan Taghi guilty of multiple murders and sentence him to life imprisonment. The verdicts of his trial are expected next year. Taghi has not been charged with De Vries’ murder.