Lord Black was already facing eight charges of fraud, carrying the possibility of 40 years in prison, but the additional charges raise that to 95 years. The case is being heard at a US federal court in Chicago.
The racketeering charge, which carries a potential 20-year prison term, alleges that Lord Black was involved in an ongoing criminal enterprise with associates at Hollinger International, of which he was chief executive and chairman.
On trial alongside Lord Black are two former Hollinger lawyers and an accountant, while his former deputy David Radler has pleaded guilty to lesser charges and agreed to testify against his former colleagues.
One of the central allegations against the defendants is that they defrauded Hollinger International and its shareholders of $84m by taking non-compete payments from buyers of Hollinger assets.
The obstruction of justice charge, also carrying a 20-year term, relates to Lord Black's actions in removing 13 boxes of documents from the Toronto offices of Hollinger Inc, the holding company through which he controlled Hollinger International.
Lord Black removed the documents contrary to a court order, out of office hours and via a back door; moreover, he was caught doing so on CCTV.
Lord Black's lawyer Edward Greenspan said that the new charges were a "blatant example of overreaching by the prosecutor". Lord Black has pleaded not guilty.
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