Police and emergency services are continuing a major search operation for a swimmer missing on the Gold Coast.

Police said emergency services were called about 6:30pm on Tuesday after reports a 20-year-old man, who is believed to be a tourist, was seen struggling in the water off Main Beach.

GC missing swimmer

Drones and a police helicopter are being used in the search for a missing tourist on the Gold Coast. (ABC Gold Coast: Danielle Mahe)

Witnesses attempted to reach the man but were unable to help and lost sight of him in the water.

Surf Life Saving Queensland’s Nathan Fife said volunteer lifeguards were also assisting authorities with the search.

“We’re just supporting the Gold Coast Water Police and searching to see if we can locate him,” Mr Fife said.

He confirmed the city’s beaches remained open and urged beachgoers to stay safe.

Lifesaver in the ocean on a jet ski

God Coast Surf Lifesavers assist in the search for a tourist missing off Main Beach. (ABC Gold Coast: Danielle Mahe)

“We’re just reminding people to swim between those patrol times and between those red and yellow flags,” Mr Fife said.

Police and Surf Lifesavers launched a search on Tuesday evening, but it was called off at 8:30pm after darkness fell.

The multi-agency search resumed at first light this morning with Water Police boats, jet skis and helicopters.

Police are asking anyone with information regarding the whereabouts of the missing swimmer to contact them.