The man, who was arrested in December, was on Monday informed that he will be remanded in custody until July 9th, police prosecutor Sonja Hedegaard confirmed.
The decision to extend the 31-year-old's preliminary detention was made behind closed doors at Copenhagen City Court on Monday. Hedegaard declined to give further details.
The man denies the charges.
Police believe the man, who is an asylum seeker in Sweden, was in contact with a 21-year-old Syrian who was sentenced to six years in prison in Germany in July 2017.
The two are believed to have planned to carry out random knife attacks on people in Copenhagen before detonating one or more bombs.
But the attack was prevented when the 21-year-old was stopped while trying to cross the border between Denmark and Germany, Ritzau reports.
He is reported to have been carrying 17,000 matches, fireworks, batteries, six walkie-talkies and kitchen knives.
Hedegaard said she could not confirm whether the police prosecution service would raise charges against the 31-year-old.