SINGAPORE, Feb 2 Gold bounced back and forth on Friday as it struggled to sustain a rally

SINGAPORE, Feb 2 (Reuters) Gold bounced back and forth on Friday as it struggled to sustain a rally the previous day, which had propelled the price to a six-month high of around $661 an ounce.

In Southeast Asia, sales of scrap picked up as jewellers and investors took advantage of higher prices, putting pressure on premiums for gold bars in Singapore Even though sentiment remained bullish after a key resistance was broken, gold would have to rise above $670 to sustain the uptrend, said dealers. Silver and platinum were also off highs, awaiting direction from the currency market.

Spot gold hit an intraday high of $657.30 an ounce and was at $655.80/656.20 an ounce by 0401 GMT, down from $657.00/657.40 late in New York.

Gold jumped to its highest since mid-July at $661.50 on Thursday as buying accelerated after it cleared the $655 hurdle.

''I think it's a reasonably bullish break for it,'' said Tobin Gorey, commodities analyst of Commonwealth Bank of Australia in Sydney.

''I am not sure if we have established the top side yet.

It's going to take out $677 and stay above there to convince everybody that it is sort of going to go up again,'' said Gorey, who pegged support at $642-$643 an ounce.

Despite the recent gains, gold was still trading well below a 26-year high of $730 an ounce hit in mid-May.

Benchmark gold futures on the Tokyo Commodity Exchange, currently December 2007, rose 12 yen per gram to 2,564 yen ($21.22), reflecting rises in New York's COMEX market.

Dealers await the release of the U.S. payrolls report, which is expected to give more clarity on the direction of U.S.

growth, especially after the Federal Reserve kept interest rates on hold this week.

In a Reuters poll, the median forecasts of economists was for companies to have added a healthy 149,000 jobs in January after an increase of 167,000 the previous month.

The dollar was little changed near 120.73 yen rebounding from a low of 120.10 yen on Thursday and down from the four-year high of 122.20 yen struck earlier this week.

The euro hardly changed at $1.3022 after rising as high as $1.3054 on Thursday, its strongest in the past month.

In the physical sector, premiums for gold bars dropped to 30 U.S. cents an ounce to the spot London price in Singapore from 50 cents two weeks ago.

''We receive a lot of scrap from Indonesia and Thailand. We had expected the price to fall below $640 this week, but it didn't happen. That's why higher prices encourage sales from jewellers,'' said a physical dealer in Singapore.

''We do see some demand but I can't say it's huge. It may be related to Lunar New Year. Gold may try to test $660 again because of a weaker dollar, and also because oil is trying to move back to $60 a barrel,'' he said.

Silver edged down to $13.58/13.65 an ounce from $13.62/13.69 late in New York on Thursday, when it rose to $13.75 an ounce -- its highest since mid-December.

Platinum fell to $1,179/1,184 an ounce from $1,182/1,187 an ounce and off Thursday's two-month high of $1,189 an ounce.

Palladium fell to $340/345 an ounce from $341/346 an ounce.

($1=120.80 yen) REUTERS CS DS1113