Both players are being watched by the Bundesliga side and their sporting director Klaus Allofs has confirmed their interest in the pair.
"He [Peeters] would fit us, but I am afraid he's too expensive for us. The same will count for Janssen, a strong midfielder who could be good value for the team," Allofs told De Telegraaf.
28-year-old Peeters and Janssen (pictured), 21, are both integral to Vitesse, but the Arnhem club are still suffering with huge debts and could be tempted to cash in.
Belgian star Peeters is still the club's record signing after they paid more than £4 million for the striker when they signed him from Roda two years ago.
Janssen would arguably command a bigger fee than Peeters as the young playmaker is one of Holland's brightest talents.
