* Harry Winston agreed last year to buy BHP's stake in mine * Minority partner says BHP did not comply with JV agreement * Partner seeks revised offer from BHP * Harry Winston share down 2.8 percent to C$14.25 on TSX Jan 17 (Reuters) - Harry Winston Diamond Corp's plan to buy BHP Billiton's Ekati diamond operations in Northern Canada hit a snag on Thursday, with a minority partner filing a lawsuit to try to block the deal. C. Fipke Holdings Ltd, which has a right of first refusal on the sale, is alleging that BHP Billiton failed to comply with their joint venture agreement, in an legal action in the Ontario Superior Court of Justice. Fipke is seeking a court order to stop the sale, unless provided with a revised offer from BHP, Harry Winston said in a statement on Thursday. Shares of Harry Winston fell 2.8 percent to C$14.25 on Thursday morning on the Toronto Stock Exchange. BHP agreed in November to sell its Ekati operations to Harry Winston for $500 million. The smaller company said it would fund the cash deal through existing resources and debt, including a $400 million term loan and a $100 million revolving credit facility. Fipke has also alleged in its claim that Harry Winston's debt financing deal has interfered with its ability to arrange its own financing, Harry Winston said. All parties in the lawsuit have a agreed to an expedited trial and appeal, which will allow for a final ruling by April 15. If the courts rule in favor of BHP and Harry Winston, the deal could close by May 15, 2013. Fipke holds a 10 percent stake in both the Ekati Core zone and Buffer zone joint ventures. The two other minority partners do not intend to oppose the deal, Harry Winston said in a statement. Harry Winston agreed earlier this week to sell its jewelry arm to Switzerland's Swatch in a $1 billion deal that leaves the Canadian company free to concentrate on its mining business.