A cyclist is fighting for their life after being struck by a van and becoming pinned under its wheels in Hamilton this morning.

Emergency services were called to the crash at the intersection of Tristram and Thackeray streets at 7.12am.

Police said the cyclist was critically injured and has been taken to Waikato Hospital.

Senior Sergeant Juliet Burgess said initial reports were of a cyclist being fatally struck by a commercial van and pinned under the wheels.

Advertisement

"However the rider was able to be revived when the vehicle was removed and that person has been taken to Waikato Hospital in a critical condition," she said.

The roundabout has been closed and diversions have been set up. Commuters are being told to expect delays.

"The Waikato serious crash unit has been called in to investigate the crash and traffic management staff are on site assisting with diversions," Ms Burgess said.

"While unable to comment further on what has occurred we can say the crash happened in wet conditions and we are asking road users to adjust their behaviour accordingly."