LONDON, Oct 1 (Reuters) - Activist investor Knight VinkeAsset Management, a top 20 investor in Xstrata, hascriticised the miner's non-executive directors for failing todemonstrate sufficient independence in its protracted mergertalks with trader Glencore. The New York-based investment firm said the "merger ofequals" recommended by Xstrata's board on Monday would inreality effect a change of control, with CEO Mick Davis replacedby Glencore's Ivan Glasenberg. Knight Vinke said it would consult other investors with aview to taking steps to strengthen the board's independence.