* Shanghai rebar falls more than 5 pct to record low
* Spot iron ore drops 4 pct to $52/T, lowest since April 21
* Iron ore stocks at Chinese ports rise to 82.16 mln T (Adds Citigroup comment, updates prices)
By Ruby Lian and Manolo Serapio Jr
SHANGHAI/MANILA, July 7 (Reuters) - Chinese iron ore futures slumped nearly 6 percent to their lowest in nearly three months on Tuesday as the steelmaking material returned to a bear market with demand in the world's top consumer waning and global supplies growing.
"Iron ore supply is picking up while steel mills are curbing output, so prices are under pressure," said Xu Huimin, an analyst with Huatai Futures in Shanghai.
The most-traded September iron ore contract on the Dalian Commodity Exchange DCIOcv1 dropped 5.9 percent to close at its exchange-set floor of 376 yuan ($60.56) a tonne, the lowest since April 13, and marking its eighth straight session of decline.
Amid slow demand in China, iron ore inventories at 42 ports across the country edged up 0.2 percent to 82.16 million tonnes on Tuesday from Friday, data from industry consultancy Umetal showed.
The spot price for iron ore delivered to Tianjin port .IO62-CNI=SI sank 3.9 percent to $52 a tonne on Monday, also its eighth consecutive day of decline and its lowest since April 21.
The spot benchmark has lost nearly 21 percent from a five-month high of $65.40 a tonne on June 11, marking its return to a bear market.
"Many steel mills are expecting iron ore prices to fall back to $45 a tonne," Xu said.
Citigroup, which has forecast prices to average at $51 this year and at $40 in 2016, said it "remains structurally bearish iron ore in the medium-term as lower prices are required to curb supply from the majors."
Down for a third year running, iron ore prices have been hard hit by a global glut as low-cost miners from Australia and Brazil boost output while Chinese steel demand slows.
The most traded October rebar on the Shanghai Futures Exchange SRBcv1 fell more than 5 percent to below 2,000 yuan a tonne, hitting 1,948 yuan - the lowest since the contract's launch in 2009. It closed down 5.2 percent at 1,957 yuan. ($1 = 6.2089 Chinese yuan) (Editing by Tom Hogue and Anand Basu)