* Iron ore at $51.90/T, lowest since July
* Ore inventories at China ports highest since June (Updates futures)
By Manolo Serapio Jr
MANILA, Oct 22 (Reuters) - Iron ore fell to a near three-month trough and looks set to sustain losses as global miners boost output further in a bid to claim more share of China's market at a time when steel demand in the world's top consumer is shrinking.
Vale VALE5.SA , Rio Tinto RIO.AX RIO.L and BHP Billiton BHP.AX BLT.L - the world's biggest and lowest cost iron ore producers - all reported increased output and shipments in the September quarter this month, shrugging off worries over a mounting global glut.
"The low iron ore price environment is leading to an intense market share war between key producers," investment bank ANZ said in a note.
"This continued focus on debottlenecking and improving efficiencies at current operations is keeping supply growth strong and likely to keep downward pressure on prices."
Iron ore delivered to China's Tianjin port .IO62-CNI=SI fell 0.4 percent to $51.90 a tonne on Wednesday, the lowest since July 27, according to The Steel Index.
The spot benchmark has fallen for the past seven days, its longest losing run since June-July. The steelmaking raw material is down 27 percent this year and is on course for a third annual decline.
Iron ore's price slump likely pushed top miner Vale back into the red in the third quarter, based on a Reuters poll of seven analysts, even as the Brazilian company lifted production to a record in the past three months. urn:newsml:reuters.com:*:nL8N12K4SC
The price of iron ore stocked at China's ports has dropped this week, reflecting lean buying interest among Chinese mills, many of whom have been limiting inventories of the raw material.
Stockpiles of imported iron ore at China's major ports stood at 83.2 million tonnes as of Oct. 16, the highest since June, data tracked by consultancy SteelHome showed. SH-TOT-IRONINV
Iron ore for January delivery on the Dalian Commodity Exchange DCIOcv1 fell as far as 362 yuan ($57) a tonne on Thursday, the lowest since Sept. 29, before closing nearly flat at 367 yuan.
January rebar on the Shanghai Futures Exchange SRBcv1 closed up 0.3 percent at 1,805 yuan a tonne, after touching a record low of 1,788 yuan on Wednesday.
Rebar and iron ore prices at 0714 GMT
Contract
Last
Change Pct Change SHFE REBAR JAN6
1805
+5.00
+0.28 DALIAN IRON ORE DCE DCIO JAN6
367
-0.50
-0.14 SGX IRON ORE FUTURES NOV
49.29
+0.31
+0.63 THE STEEL INDEX 62 PCT INDEX
51.9
-0.20
-0.38 METAL BULLETIN INDEX
52.79
-0.14
-0.26
Dalian iron ore and Shanghai rebar in yuan/tonne Index in dollars/tonne, show close for the previous trading day ($1 = 6.3485 Chinese yuan)