U.S. gold futures hit a six-month high of $1,000 and spot gold also rose to six-month high on Tuesday as the dollar's weakness, concerns about the sustainability of global economic recovery and worries about future inflation underpinned sentiment.

Spot gold rose as high as $997.90, its highest since February, when it briefly topped $1,000.

U.S. gold futures for December delivery touched $1,000 briefly before slipping to $999.0 per ounce. Futures settled at $996.70 on Friday.

The contract rose to $999.50 on Thursday, the highest price since February. U.S. markets were closed on Monday for Labor Day holiday.

Futures were always going to lead the way above $1,000, so spot can't be far behind. Gold's rising price is due to uncertainty all the way from personal investors right through to institutions, said Sandra Close, analyst for gold research group Surbiton Associates.

There are questions out there over the health of economies, where interest rates are going. All that encourages gold hoarding. There's potential to see the price go even higher, she said.

Some analysts have said the higher gold price reflected uncertainty across markets on how central banks will untangle themselves from fiscal stimulus aimed at reviving economic growth, as well as dollar weakness.

The Group of 20 finance ministers and central bankers said over the weekend they would not remove economic stimulus until the global recovery was well entrenched. Traders said volume was not large and as futures slipped soon after hitting the key level, and with spot struggling to extend gains toward $1,000, prices might languish during Asian trade.

I think these high levels could trigger selling ... and it might be difficult for gold to sustain the $1,000 level, said Shuji Sugata, manager at Mitsubishi Corp Futures & Securities in Tokyo.

However, we need to watch the dollar-euro rate and technical factors as these could prompt gold to move higher.

Investment flows took a break, with the world's largest gold-backed exchange-traded fund, the SPDR Gold Trust, saying holdings stood at 1,077.63 tonnes as of September 7, unchanged from Friday.

The dollar steadied after falling the previous day as a weekend meeting of global finance chiefs boosted investor appetite for growth-related riskier assets like commodities and stocks.

(Additional reporting by Jim Regan and Miho Yoshikawa)