Alfa Bank wants more money from RUSAL, may sue

* Alfa wants RUSAL to pay interest due on repaid debt * RUSAL says will pay MOSCOW, Oct 23 (Reuters) - Alfa Bank wants Russian aluminium giant UC RUSAL to pay interest due on debts that have already cleared and is ready to go to court over the issue, the lender's deputy chief executive, Vladimir Tatarchuk, said on Friday. RUSAL said in a statement it would pay any outstanding liabilities once their size has been determined. Last month, debt-laden RUSAL -- controlled by Russian billionaire Oleg Deripaska -- said it had repaid $85.9 million to Alfa Bank after the private lender threatened to pursue the bankruptcy of two RUSAL units. Tatarchuk said RUSAL had paid all of the original debt and some of the interest on it, but had not paid the penalties and fines which had accumulated. "We plan to get all the interest which was not paid by RUSAL," Tatarchuk told reporters. "If we do not manage to agree with RUSAL's units, then we do not exclude filing a law suit." RUSAL, whose outstanding debts total around $16.8 billion, said in an emailed statement it would meet its obligations. "RUSAL has always fulfilled, is fulfilling and will fulfil its obligations relating to the credit agreement with Alfa Bank," the statement said. "We have never refused to pay the penalties...and intend to pay them once the size has been determined -- either through a peaceful agreement or by a court decision." RUSAL is in the process of preparing a $2 billion IPO in Hong Kong as part of its recovery plan, sources have told Reuters. (Reporting by Oksana Kobzeva and Polina Devitt; Writing by Toni Vorobyova)