* Dalian iron ore set to drop more than 8 pct this week
* Shanghai rebar down nearly 3 pct on day, 5 pct on week
* Oil, gold also down in broad commodities fall
By Josephine Mason
BEIJING, May 5 (Reuters) - Chinese iron ore futures plunged to their lowest since January on Friday, extending this week's losses and dragging steel down as well, with investors liquidating long positions amid growing worries about slowing construction and infrastructure demand.
This week's sell-off put one of China's largest commodity derivatives markets on track to drop 8.6 percent for its worst weekly performance since December.
"Reining in of excessive local government debt and the shadow banking sector in China has been high on the central government agenda, leading to concerns that tighter liquidity will affect completion of some large infrastructure projects," said commodities broker Sucden in a research note.
Iron ore on the Dalian Commodity Exchange was down 6.7 percent at 466 yuan ($67.58) per tonnes at 0251 GMT, on track for its biggest daily drop since late November. Earlier in the session, it hit 458.5 yuan, its weakest since Jan. 9.
The most-active rebar contract on the Shanghai Futures Exchange was down 2.6 percent at 2,929 yuan a tonne, set to post a 5 percent drop for the week.
The selling spree on Friday was spread across the broader global commodities markets. Oil prices were marooned near five-months lows after a near 5 percent fall in the previous session on concerns over rising U.S. supply, wiping out all of the price gains since OPEC's move to curb output. Gold was also on track for its worst week since November.
China's import data due for release on Monday will be keenly watched for signs of the world's second-largest economy's appetite for raw materials.
March arrivals of iron ore were the second highest on record, as steel output hit a record, but analysts and traders have warned of slowing demand for end-products.
Data earlier this week showed iron ore shipments to China from Australia's Port Hedland terminal, used by top miners BHP Billiton and Fortescue Metals Group, rose to 34.86 million tonnes in April from 31.5 million tonnes in the previous month.
Iron ore for delivery to China's Qingdao port .IO62-CNO=MB slid 5.1 percent to $65.20 a tonne on Thursday, its lowest since April 19, according to Metal Bulletin. It marked the steepest one-day decline for the spot benchmark since April 12.
Coking coal futures on the Dalian exchange fell 4.4 percent to 1,024.5 yuan a tonne. Coke dropped 3.2 percent to 1,476 yuan.
$1 = 6.8960 Chinese yuan Reporting by Josephine Mason; Editing by Tom Hogue