Shares in Talvivaara Mining, the Finnish miner which has been rocked by a series of waste water leaks, slid after it withdrew its nickel production guidance for this year.It had hoped to produce 18,000 tonnes of nickel in 2013 but has ditched this target after producing just 4,508 tonnes in the first half. Production has been impacted by excess water.The miner, once lauded for its pioneering metals extraction process known as bioheapleaching, has seen its shares plummet over the past year after being hit by a series of problems, including a 11-day leak last November at its Sotkamo mine. Chief executive Pekka Pera said: "Revival of the leaching performance has been somewhat slower than we had hoped for and some uncertainties relating to the short-term leaching rate still remain. This has forced us to withdraw our production guidance for the current year until we get more clarity into the near term leaching recoveries." Talvivaara had to tap investors for €261m in April and earlier this month said it may axe up to 250 staff because of the weak nickel prices.Investec analysts said: "It clearly remains an uphill battle to get operations on track, and the weak nickel price will exacerbate the situation reinforcing the company's need to focus on costs and performance ahead of a refinancing requirement of over $225m in 2015 that will be increasingly challenging if operation continue to under perform." Shares in Talvivaara were down 8.5% to 9.61p by 14.32 on Friday.TB