The pair, an Iraqi, 46, and a Nigerian, 29, arrested yesterday, would be held until today when they will either go before a judge or be released, prosecutor's office spokesman Thomas Steinkraus-Koch said.
The men were questioned in southern Bavaria yesterday afternoon.
"From what we know now there is no concrete threat," Bavarian police added in a statement.
According to the Suddeutsche Zeitung daily's online edition, one of the suspects was arrested in Munich while the other was picked up in Furstenfeldbruck in Bavaria.
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Although initial investigations failed to establish any imminent threat, police decided to question the men immediately.
Searches were carried out but no suspicious items were found, a police spokesman said.
Since the November 13 attacks in Paris that killed 130 people, German authorities have repeatedly said they believe Germany faces the threat of jihadist attacks.