A boat which was "in distress" near Tauranga in the early hours of this morning may have sunk.

The two on board were rescued, but local Coastguard manager Dane Robertson says efforts to find the missing vessel have been unsuccessful.

The boat let off two rocket flares to signal they were taking on water. A pilot boat and "a large ship" also responded to the scene.

"We were alerted at just after 2am. Our crew had six on board, and were able to transfer the people over to return them safely to shore. The water was about halfway up the engine block." says Dane.

"When we left the vessel was not underwater. We tied a number of windy buoys around it, so if it did sink, it would indicate something is there."

Dane says Coastguard let the Harbourmaster know where the boat was and how fast it was travelling.

"It was 20 knot winds and about one and a half to two metre swells."

Both the Harbourmaster and an aircraft searched for the vessel. Dane says because they couldn't find it, they believe it "may have sunk".

Dane also thanks the duty officer and crew who attended the rescue.

"They got home at about 5.30am, and then had to get dressed and go to work. I'd really like to thank the team from delta crew. They are achieving our mission of saving lives at sea."