The move came as the board of Hollinger International convened an emergency board meeting to discuss the deal, which many see as a bargain for the Barclays.
Relations between Lord Black and the board of Hollinger International are already very poor with the board sacking him as chairman over the weekend and saying it would sue him for £200m.
Lord Black, who controls Hollinger Incorporated, has agreed to sell that company to Press Holdings International, which is owned by Sir David and Sir Frederick Barclay.
In a statement Lord Black defended the deal he had cut. "The offer by Press Holdings International will provide substantial value to all shareholders of Hollinger Inc as well as benefiting Hollinger International by allowing the company's fine media properties to move forward without further distractions or financial uncertainty," he said.
He added that as a result appropriate legal action was being taken to prevent any interference with the completion of the deal.
A report in the Financial Times says that the board could meet as early as today to assess the impact of the deal and discuss whether to oppose it. The Barclay brothers have said their deal with Lord Black is "irrevocable".
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