Police say dozens of under-age drinkers had to be sent home during the Fat as Butter music festival in Newcastle at the weekend.

Thousands of young people converged on the foreshore on Saturday for the 15 plus event which is now in its sixth year.

A Hunter Street hotel has been shut down until 5:00pm (AEDT) this afternoon because police were concerned the venue would pose a significant risk with thousands of young people in the city.

Acting Inspector David Checkley says several underage drinkers did not get to enjoy the festival to the end.

"We had 45 young persons that were detained because of intoxication and returned to their parents," he said.

"There would have been some pre-loading involved in that, prior to the event, and surely some would have been from the event as well.

"We had about 110 drug dog indications which resulted in searches, with about 19 drug detections."

Acting Inspector Checkley says police are disappointed in the number of under age drinkers.

"It is frustrating, " he said.

"It is an aspect of the Newcastle city blueprint that we're trying to get on top of.

"There's been some significant inroads in that area but it is disappointing to see that young people are turning up to these events intoxicated, especially with police working closely with the promoter to ensure a safe and enjoyable event."