* Rain for dry Argentine belts keeps onus on high supply
* One-year low for palm oil, China import rules also weigh
* Wheat retreats from 2-1/2 week peak (Updates with U.S. market open, updates prices, adds analyst quote, changes byline, changes dateline from PARIS/SINGAPORE)
CHICAGO, Dec 22 (Reuters) - U.S. soybean futures held near three-month lows on Friday and were on track for a third straight weekly decline as forecast rain in Argentina eased concern about a potential supply risk.
Corn hovered near previous levels, lifted at times by short-covering ahead of the Christmas holiday weekend, while wheat slipped from two-week highs.
Trading volumes were light in the holiday-shortened session. Markets will close at 12:05 p.m. CST (1805 GMT) on Friday and will remain closed on Monday.
Weekend showers are forecast for Argentine crop belts, which on top of recent rainfall has eased concerns about drought in the world's third-largest soybean exporter.
"Argentina started dry and the soybean market in particular had built some premium in. We've seen that premium completely erased here in the last couple of weeks because of the improvement in weather," said Joe Vaclavik, president of Chicago-based Standard Grain.
Soybeans have also been curbed by a slide in palm oil futures. Benchmark prices in Malaysia fell to a 16-month low although they later recovered, helping CBOT soybeans come off their low.
More stringent specifications for U.S. soybean imports in China, the top importer, have pressured futures this week as they could curb buoyant Chinese demand.
Chicago Board of Trade January soybeans were 3/4 cent higher at $9.49-1/2 a bushel at 11:10 a.m. CST (1710 GMT) after earlier sinking to a low of $9.46-1/2, the lowest for the most actively traded contract since Sept. 13. Soybeans have closed lower in 11 of the previous 12 sessions.
Wheat prices eased as traders squared positions ahead of the holiday weekend after two sessions of gains and as U.S. weather forecasts showed the risk of freeze damage to winter crops has lessened in recent days.
The grain has also been supported by an increase in export demand after futures hit life-of-contract lows last week.
Millers in Thailand bought 150,000 tonnes of U.S. spring wheat and hard red winter wheat in recent deals, traders said. Asian livestock producers, meanwhile, have stepped up purchases of soft red winter wheat, with sales last week at the highest in three years.
CBOT March wheat was down 2-1/2 cents at $4.24-1/2 a bushel after earlier rising to a 2-1/2 week high of $4.29. March corn futures gained 1/2 cent to $3.51-3/4 a bushel, the highest since Dec. 13. Both were on pace for their first weekly gains in three weeks. (Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Elaine Hardcastle and Susan Thomas)