LONDON, April 17 (Reuters) – Weak industrial data in top base metals consumer China weighed on prices on Tuesday, but aluminium was expected to resume its rally as U.S. sanctions disrupt supplies from the world’s No. 2 producer Rusal. Chinese industrial output expanded 6.0 percent in March year-on-year, the slowest pace in seven months, while fixed asset investment for January-March also came in below expectations. China’s economy, however, grew 6.8 percent in the first quarter of 2018, slightly faster than expected. “IP and fixed asset investment missed the consensus so that was a dampener and put a bit of constraint on the metals,” said Robin Bhar, head of metals research, Societe Generale. A fall in German investor morale to the lowest level since November 2012 and a slightly firmer dollar also knocked sentiment. Benchmark aluminium on the London Metal Exchange was volatile, touching a 6-1/2 year peak of $2,435, then slipping into negative territory in early European trading. It fell 1.1 percent to $2,372 a tonne in official open outcry trading. “With all the uncertainty around Rusal, there’s no way but for the price to head higher still to incentivise more production from elsewhere,” Bhar said. While a fair price was around current levels, speculators and investors could take it as high as $2,800-$3,000, he added. “We will go above fair value because of the unprecedented situation and the involvement of speculators and investors.” United Company Rusal accounts for 6-7 percent of global aluminium supply. ALUMINIUM STOCKS: More aluminium arrived into LME warehouses, which traders said was likely to be Rusal material, pushing up LME inventories by 52,125 tonnes to 1,412,400 tonnes, the highest since June last year. JAPAN: Major Japanese trading houses have asked Rusal to stop shipping refined aluminium and other products in light of U.S. sanctions and are scrambling to secure metal elsewhere, industry sources said. COPPER: LME copper shed 1.1 percent to trade at $6,833 a tonne in official rings after on-warrant LME stocks, those not earmarked for delivery, climbed 10,950 tonnes to 313,450 tonnes, indicating healthy supplies. NICKEL: Nickel was the biggest decliner on the LME, bid down 2.7 percent at $13,950 a tonne after failing to trade during official activity. With nickel the biggest speculative long of the LME complex, according to estimates from broker Marex Spectron, it appeared some bulls were liquidating positions, traders said. *PRICES: Zinc was bid down 0.4 percent at $3,125 a tonne in official rings, lead was bid down 1.1 percent at $2,343 and tin traded up 0.2 percent at $21,075 a tonne.