* Prices jump 1 pct to highest since April 15
* Liquidity thin as London closed for May Day holiday
* SPDR outflows totalled almost 10 tonnes last week
(Updates throughout, changes dateline, pvs SINGAPORE)
LONDON, May 5 (Reuters) - Gold hit three-week highs on Monday in thin trade, extending the previous session's gains, as simmering tensions in Ukraine, a retreat in the dollar and a break above a key chart level fuelled buying.
Investors remained cautious on whether the gains can be sustained, however, as several markets were closed and as outflows from the top physical gold exchange-traded fund continued to indicate bearish sentiment.
Spot gold was up 1 percent at $1,312.60 a troy ounce by 0930 GMT, after rising to $1,315.00 earlier, its highest since April 15. Liquidity is expected to be thin with London markets closed for the May Day holiday.
U.S. gold futures for June delivery were up $9.90 an ounce at $1,312.80.
On Friday, the metal hit a one-week low of $1,276.60 after strong U.S. jobs data, but reversed losses to end the day up 1.3 percent on a sharp increase in the number of people dropping out of the workforce and rising Ukraine tensions.
"Gold is trading near the highest in three weeks as Ukraine once again attracts some safe-haven demand and the dollar continues to trade on the weak side," Saxo Bank's head of research Ole Hansen said.
"The weakness following the strong U.S. jobs report on Friday was quickly reversed and the subsequent rally of $30 may have given the bulls back some of the confidence that has been missing for the past few weeks."
"But the move so far has not been convincing, so we're still not sure whether it will stick," he added. "For now, let's see whether a foothold can be established above $1,300."
Gold's 200-day moving average, a key chart level, is located at that level. Traders said a break above there on Friday fuelled confidence in further gains.
Pro-Russia militants stormed a Ukrainian police station in Odessa on Sunday and freed nearly 70 fellow activists as the country's leaders said its police force was undermined by graft or collaboration with separatists.
CHINESE BUYERS ACTIVE
In the physical markets, Chinese buyers were active, precious metals house MKS said in a note.
"We had a bit of an unexpected surprise when China opened up, with some heavy buying going through," it said.
"The Shanghai Gold Exchange traded up to a premium of around $3-5 over spot and more importantly the Shanghai Futures Exchange traded higher than the SGE for the first time in weeks, suggesting that the Chinese general public (non institutional) investors were in covering shorts."
Weakness in investment has pressured gold in recent weeks. The SPDR Gold Trust, the world's largest gold ETF, said its holdings fell 2.70 tonnes to 782.85 tonnes on Friday, bringing its outflow for the week to nearly 10 tonnes.
Hedge funds and money managers cut their bullish bets in gold futures and options, data from the Commodity Futures Trading Commission showed on Friday.
Silver was up 0.9 percent at $19.61 an ounce, while spot platinum was up 0.6 percent at $1,440.30 an ounce and spot palladium was up 0.3 percent at $810 an ounce.
South Africa's Association of Mineworkers and Construction Union (AMCU) said on Monday its striking members had rejected the latest wage offer by the world's three biggest platinum mining companies.
The strike has been running for nearly four months at Anglo American Platinum, Lonmin and Impala Platinum , and has hit 40 percent of global production of the precious metal.
(Additional reporting by A. Ananthalakshmi in Singapore, editing by William Hardy)