NEW YORK, Dec 31 - U.S. copper was up half percent to 16-month highs on Thursday as fund buying and a looming mine strike in Chile put the red metal on course for a 140 percent gain this year, its best in at least 20 years.

For detailed report on global copper markets, click on [MET/L] * Benchmark copper for March delivery HGH0 up 1.85 cents, or 0.5 percent, at $3.3635 per lb by 10:25 a.m. EST (1525 GMT) on the New York Mercantile Exchange's COMEX division.

* Range from a session low of $3.3430 to $3.3790 per lb, a high last achieved on Aug. 21, 2008.

* On a spot continuation basis for a first month contract HGc1, COMEX copper showed a gain of nearly 140 percent for 2009, the highest on Reuters charts that went as far back as 1989.

* The dollar fell against most currencies [USD/], helping fuel the run-up in copper which drew its strength largely from the favorable investment outlook for 2010 and the strike that could likely take place at Chile's giant Chuquicamata copper mine as nearly as next week. [ID:nN30198207]

* Benchmark copper for three-month delivery MCU3 on the London Metal Exchange closed at $7,375 a tonne in the rings, up 139 percent on the year. It earlier touched $7,423.75, its highest since Sept. 1, 2008.

* But copper prices are still some way off their all-time high of $8,940 a tonne on the LME and nearly $4.30 per lb on the COMEX notched in July, 2008, before the global economic downturn caused markets to tumble.

* Part of the drag on prices this year has been creeping inventories of copper, mainly at warehouses monitored by the LME. Copper stockpiles in LME warehouses rose again at the close of Wednesday's session, rising 6,375 tonnes to touch above 500,000 tonnes, their highest levels since April.

(Reporting by Barani Krishnan; Editing by Marguerita Choy)