Lord Black resigned when irregularities came to light

The twin tycoons on Sunday announced the purchase of Lord Black's shares in Hollinger, which publishes titles including the UK Telegraph stable.

But a tender to sell Hollinger is still proceeding, with a number of likely bidders already lined up.

And US regulators are seeking to block any sale by Lord Black.

The Securities and Exchange Commission has sued in an attempt to forestall a sale until its investigation into Hollinger's financial affairs is concluded.

Lord Black was ousted over the weekend as Hollinger chairman amid allegations of financial irregularities, which he denies.

Tender pending

Meanwhile, a review of Hollinger International's businesses by investment bank Lazard is set to continue independently of the Barclay brothers' bid.

It's a very shrewd move to go direct to Black and not await the possibility of the bank selling off bits of the organisation Roy Greenslade Media analyst Profile: The Barclay brothers

It raises the prospect of the company's main assets being put up for auction before the Barclay brothers' offer for the holding company - Hollinger Inc - is completed, according to the Financial Times.

The tender under way for control of Hollinger International has attracted interest from a string of bidders, including Express newspapers' owner Richard Desmond.

Express Newspapers and the Telegraph Group jointly own the Westferry printing plant in east London.

'Distressing' sale

While the Barclays' deal does not scupper the tender, it effectively puts them in a far stronger position than their rivals.

Lord Black said the sale of his holding in Hollinger was "distressing", but his newspapers would be in "good and caring hands".

Hollinger's global newspaper empire includes: The Daily Telegraph, Sunday Telegraph and the Spectator magazine, UK The Jerusalem Post, Israel The Chicago Sun-Times, US

In a statement he said: "It will be distressing to part from the Telegraph newspapers, the Spectator, the Chicago newspapers and the Jerusalem Post, in particular, but these fine titles must not be hobbled any longer by the current controversies and financial uncertainty.

"They will be in good and caring hands and we will be able to focus exclusively on resolving current legal and public relations concerns."

The Barclay deal gives them Lord Black's 30% stake and his 73% voting rights at Hollinger, which would be a substantial disincentive for any other potential bidders.

The brothers have valued the firm at �260m, double its closing price on Friday night.

According to sources close to the deal, the brothers intend to take Hollinger private, and see it as a long-term investment.

It is reassuring that at a time when we're in difficulty there are people who want to buy the newspaper George Jones The Daily Telegraph Profile: Conrad Black

Media analyst Roy Greenslade said they had been "shrewd" to go direct to Lord Black and not wait for the business to be sold off by a bank.

"This way they get total control and do so very quickly," he said.

Political clout

The Barclays, who have a reputation as reclusive and patient investors, own a varied portfolio including the Scotsman newspaper group, the Ritz hotel and Littlewoods catalogues.

Control of the Daily Telegraph, the UK's most popular broadsheet and a strong supporter of the Conservatives, will bring them political clout.

Some journalists at the paper on Sunday welcomed the deal.

George Jones, political editor, told BBC News: "I would have thought that they were broadly of the conservative mind of businessmen so I think that they will continue with the political direction of the paper.

Lord Black is also being investigated by the Hollinger board, which alleges a range of financial abuses including excessive management fees paid to Ravelston, Lord Black's holding company.

There could also potentially be regulatory issues, often a major factor in media takeovers, and the deal will be referred to Ofcom, the UK communications watchdog.