Chinese authorities have fined Procter & Gamble Co's Crest toothpaste division nearly $1 million for what regulators say is false advertising, a Shanghai watchdog said on Tuesday.

The U.S. brand overplayed the effects of some of its toothpaste and used digital software to "touch up" images used in advertising to make teeth look whiter, the Shanghai Administration for Industry & Commerce said in a post on its official Sina Weibo microblog.

The regulator said it has fined Crest 6.03 million yuan ($963,000), an amount described by Chinese media as the biggest fine of its type on record. Crest said on its official Chinese microblog on Tuesday the advert in question was pulled in the middle of last year, without disclosing whether it plans to contest the fine.

P&G couldn't immediately be reached for comment.

China has been trying to strengthen consumer protection laws and beef up punishment for businesses found to have misled shoppers. Global firms like iPhone maker Apple Inc, Volkswagen AG (VOWG_p.DE) and camera maker Nikon Corp have been caught under the regulator's glare in recent years.

Crest leads China's fast-growing toothpaste market along with rival Colgate-Palmolive Co and local brands Darlie and Yunnan Baiyao Group Co Ltd. It said in its Sina Weibo post on Tuesday that all the firm's products went through rigorous testing in China before going to market in order to comply with Chinese law.

"Crest has always done its utmost to produce and sell high-quality, safe products for consumers," the brand said, adding its standards were the same all around the world.