UPDATE: The three men whose boat capsized off Fraser Island this morning have been rescued.
A representative from Coast Guard Tin Can Bay confirmed one of their vessels picked up the men, after the stricken boat was spotted by the AGL Action Rescue Helicopter.
The men were a bit shaken up, but otherwise okay, the representative said.
They were on their way from the Gold Coast to the Whitsunday's when their 14m cruiser sank, he said.
EARLIER: Hervey Bay Water Police are on a rescue mission for three people whose boat has reportedly capsized off Fraser Island.
A Water Police spokesman confirmed they had been told the vessel had capsized at the Wide Bay Bar, which is on the southern end of Fraser Island.
He said there were reports that three people were in the water but could not give any further details at this stage.
An AGL Action Rescue Helicopter spokeswoman said a crew was on the way to the region to assist with the rescue.
A police media representative said the report came in at 11.25am and Rescue 511 and Coast Guard personnel from Tin Can Bay and Sandy Straits were en route.
The Australian Marinas Guide states the Wide Bay Bar is well known by boaties as being one bar that demands the highest respect for attempting a crossing.
"The entrance is marked by lit beacons but it is recommended that mariners contact Tin Can Bay Coastguard to obtain the latest information on bar conditions and position before attempting to cross it," the AMG advised.