Copper extended gains in futures trade today by Rs 0.20 or 0.06 per cent to Rs 335.25 per kg,as traders covered up their short positions amid firming trend overseas. It ended 0.05 per cent higher at Rs 332.10 per kg in yesterday's trade. Good demand for the metal in the domestic markets,also supported the upward march in copper futures here. On the Multi Commodity Exchange platform,copper for delivery in June contract rose Rs 0.20,or 0.06 per cent to Rs 335.25 per kg,with a turnover of 1,228 lots. The metal for delivery in April contract also edged up Rs 0.10,or 0.03 per cent to Rs 332.20 per kg,clocking a turnover of 1,940 lots. Analysts said,covering-up of short positions by speculators ahead of month-end and firming trend in base metals in global markets,helped copper futures to rise. Meanwhile,at the LME copper three-month rose USD 99 to USD 7,499 early while at Shanghai,the metal up 850 yuan or 1.40 per cent to 61,450 yuan per tonne.