Wellington (AFP) - New Zealand's world No. 1 Lydia Ko has "hit the panic button" by sacking her caddie in response to a form slump, high-profile bagman Steve Williams said on Wednesday.

Ko's Australian caddie Jason Hamilton confirmed this week that he had parted ways with the 19-year-old after almost two years together.

"She felt like now was a good time to make a change," Hamilton told golfchannel.com. "She said she thought it would be good to get a different set of eyes out there."

After rewriting the amateur record books, Ko enjoyed a dream start to her professional career and claimed 14 LPGA titles, including two Majors.

But the Korean-born Kiwi's form has faltered lately and she finished 51st in the Korea LPGA Championship that wrapped up on Sunday.

Fellow New Zealander Williams, who has caddied for Tiger Woods, Greg Norman and Adam Scott, said dumping Hamilton looked like a knee-jerk reaction.

"It's very surprising news, this is the first form slump of any kind she's had as a professional, and it's only a slight form dip," he told Fairfax New Zealand.

"It doesn't seem like a reason to release her caddie. Maybe they've hit the panic button a bit early."

Ko, who went into the Rio Olympics as favourite but had to settle for silver, has not named a replacement for Hamilton.