(Reuters) - Gold bullion plunged nearly 4 percent to below $1,200 an ounce on Thursday as a major technical break and an early equities sell-off triggered heavy fund selling, fueling the biggest one-day decline in five months.

Disappointing U.S. and Chinese economic indicators drove a major slide in oil, copper and some stock markets. The dollar fell to a seven-month low against the yen, and bullion got caught in the downdraft as investors cashed in profits in the best-performing major asset of the second quarter.

Silver and platinum group metals also tumbled as signs of a slowing economic recovery and lackluster U.S. auto sales hurt the investment appeal of industrial metals.

"What you are seeing is clearly a nervous feeling about all assets, whether they be tangible or intangible, paper or not. The overall mood is bearish and metals may not be the safe haven that you can just bank on," said Scott Meyers, senior analyst at New York-based Pioneer Futures.

Spot gold hit a near one-month low of $1,197.25 an ounce. It was last at $1,197.85 an ounce at 3:12 p.m. EDT, against $1,241.35 late in New York on Wednesday. It gained 11.7 percent in the March-June quarter.

U.S. gold futures for August delivery settled down $39.20, or 3.2 percent, at $1,206.70 an ounce.

Gold held firm in the last two days in the face of heavy losses in the stock markets. However, gold's eventual decline versus the S&P 500 index on Thursday was similar to a pattern in May, when the market succumbed to liquidation by funds who needed to cover margin calls in weaker markets.

"Gold has been caught up in commodity liquidation after poor data and as equities (fall)," said Simon Weeks, head of precious metals at the Bank of Nova Scotia.

"Usual story -- selling first as people need cash... and then further down the road, the gold as a currency demand will kick in."

In another repeat of mid-May market action, gold traded in close tandem with the U.S. dollar on Thursday, maintaining a link that was strongest at the height of the European debt crisis in May, when the two were generally rising.

The decline accelerated after prices broke cleanly below the five-month rising channel in place since February, and could be set for further losses after dropping below the 50-day moving average at $1,212.64 and the psychological $1,200 mark.

A sharp retreat of the relative strength index (RSI) also signaled bullion investors are taking profits in an overbought market, analysts said. Open interest in COMEX futures had risen to a record high on Wednesday.

"You have too many people who are bullish on gold, and too many cooks spoil a broth. So, some of the weaker hands are getting washed out here," said Adam Hewison, president of Maryland-based MarketClub.com.

U.S. equity markets logged a fourth straight day of declines after data showed slower-than-expected manufacturing growth in June and a sharp drop in May pending home sales. Eyes now turn to Friday's non-farm payroll data. .N

Among other precious metals, silver was at $17.80 against $18.55 on Wednesday.

Platinum group metals markets are digesting news of flat U.S. auto sales in June, as major automakers said they saw no sign of the definitive second-half recovery the battered industry had expected early in the year.

Platinum was at $1,498.50 an ounce against $1,531.50. Palladium was at $428.50 against $442.

(Additional reporting by Jan Harvey in London; Editing by David Gregorio)