Swimmers at a popular Auckland east coast beach are being warned to stay out of the water after two large sharks - one the size of a small boat - were spotted close to shore this morning.

Auckland Council is warning swimmers and recreational boaties at Eastern Beach to exercise caution after a confirmation there were sharks in the location.

At least two, believed to be great whites, have been spotted just 600m from shore.

A person who was on the water and laid eyes on the pair said one was at least 5m long, measuring just a little smaller than his craft.

"We were in a 26-foot (8m) boat and alongside one of them," said the boatie who did not want to be named.

"They are very large. We came back in. We did not want to be out there, to be honest."

He said he alerted coastguard about the danger they posed.

"We were more worried about the kids on the beach and people on jet skis," he said.

It comes a day after a popular Auckland west coast beach was cleared due to a shark sighting.

An alert was posted on Auckland Council's Safeswim website, advising against swimming at Muriwai Beach.