Phil Mickelson's coach Butch Harmon on Tuesday said he was "shocked" after Tiger Woods' caddy was caught in an extraordinary outburst against the world number three.

Harmon, who has also coached Woods, described caddy Steve Williams' comments as "deplorable" after the New Zealander called Mickelson a "prick" and questioned his relationship with the world's top player.

"I can't believe he said what he said. I think it's deplorable he would say something like that," said Harmon, adding that he was "extremely upset."

"Golf is a game of honour and integrity and that was a very uncalled for remark. I don't think it's any reflection of what Tiger thinks of Phil Mickelson."

Williams' remarks, which included an anecdote disparaging Mickelson's weight, were apparently made during a speech at a charity golf event. But he confirmed them later when approached by New Zealand media.

"I was simply honest and said they don't get along. You know what it's like. You're at a charity event and you have a bit of fun," he told the Sunday Star-Times.

The candid comments were not welcomed by either Woods or Mickelson.

Woods issued a statement saying he was "disappointed," while Mickelson called them "grossly inaccurate and irresponsible."

Harmon said he could not understand why Williams lashed out at Mickelson, Woods' former Ryder Cup team-mate.

"Phi Mickelson is one of the most popular players in the world, every bit as popular as Tiger Woods," he said.

"He's a nice guy, all the guys like Phil so I don't know where Steve was coming from with that comment. Personally, I would assume he would wish he'd never made it.

"I would have loved to have heard a recording of the conversation between (Williams) and Tiger. I worked with Tiger for 10 years and I can tell you he wouldn't have been very happy with that."

Harmon is in the gambling enclave Macau to unveil the revamped Caesars Golf course, which includes Asia's first Butch Harmon School of Golf.

AFP