A man has been killed in a shark attack on the Gold Coast, the second person to be attacked in the coastal canals this summer.

Police say the elderly man was found just before 10:00am this morning at Burleigh Lake.

It is believed a person using a surf ski discovered the body.

In the week before Christmas a 23-year-old man died while swimming in a Burleigh Waters canal at night.

His father found the body several days later with a large leg wound.

A post mortem examination determined he had been bitten by a shark before he died.

Ambulance officers today are warning people not to swim in Gold Coast canals as they are inhabited by sharks.