LONDON, July 23 (Reuters) - Aluminium rebounded on Monday as investors bought back bearish positions after a U.S. official raised the prospect of lifting sanctions on Russia's Rusal. Cancelling sanctions on Rusal, the world's biggest aluminium producer outside of China, would ease fears of a supply shortage. However, some investors who had placed short positions in expectation of sanctions being lifted were now liquidating them, said Julius Baer analyst Carsten Menke. "For aluminium, it's probably sell the rumour, buy the fact," Menke said. Some consumer buying was also seen, Marex Spectron's Alastair Munro said in a note. U.S. Treasury Secretary Steven Mnuchin told Reuters the Treasury was open to removing Rusal from a U.S. sanctions list, adding that the objective was "not to put Rusal out of business". Three-month aluminium was the biggest gainer on the London Metal Exchange, rising 1.4 percent to $2,057 a tonne by 1030 GMT. Aluminium soared to a seven-year peak of $2,718 in April after sanctions were slapped on Rusal, but prices tumbled after the United States initially said there was potential for the sanctions to be lifted. Prices lost further ground over the past two months on worries of weaker demand because of trade tensions and a slowdown in top metals consumer China. * ALUMINIUM INVENTORIES: On-warrant LME aluminium inventories -- those not earmarked for delivery -- slid by 30,275 tonnes to 1,011,725 on Friday, data showed. * ZINC: LME zinc rose 1 percent to $2,599.50 a tonne on short-covering because of a lack of immediate available supply, traders said. LME data showed a large short in August futures, while a single holder controlled more than half of LME inventories. * STEEL: Zinc, mainly used in galvanising steel, also received a boost as China's steel futures rose on Monday for a third session in four on concerns of tight supply. * COPPER: LME copper rose 0.2 percent to $6,161.50 a tonne. Last week prices fell for a sixth week in a row, hitting their lowest in a year at $5,988. * STRIKES: Labour negotiations at Chile's Escondida copper mine, the world's largest, are deadlocked without signs of progress toward an agreement a little more than a week before the current contract expires. * COPPER DEFICIT: The global world refined copper market showed a 98,000 tonne deficit in April, compared with a surplus in March, the International Copper Study Group said. * SCRAP: China's June scrap copper imports dropped by 39.8 percent year on year to 200,000 tonnes, Chinese customs data showed.