Ryan Nelsen believes West Ham have issued a statement of intent by tying Winston Reid to a new deal.
Tottenham are keen for striker Shaquile Coulthirst to continue his development out on loan after his spell at Southend.
The 44-year-old, who moved to the Euroborg last May, will be out of contract in the summer and it has been decided not to offer him an extended deal.
Groningen have struggled for consistency this season and currently lie 11th in the league, six points away from the European play-off places.
Maaskant met club representatives this morning, where it was agreed he will step down in May.
"The atmosphere within FC Groningen is excellent," he told the club's official website.
"I work very well with the players, the technical and medical staff and the management here.
"This decision has been taken by both parties and I can honestly say I think FC Groningen is an amazing club."
Managing director Hans Nijland added: "I would like to compliment Robert Maaskant.
"He has acted very professionally and we are absolutely convinced he will continue to work in a dignified and professional manner until the end of the season as we look to achieve our sporting goals and ambitions."