BSkyB, 39-percent owned by 21st Century Fox, said it had agreed to buy Fox's 100-percent stake in Sky Italia and its 57.4-percent interest in Sky Deutschland.
The new project, named "Sky Europe" by observers, is being seen as a bid by media mogul Murdoch to strengthen his European television operations as the telecommunications sector enters the market to screen live football matches featuring some the world's biggest clubs.
Analysts said the deal would give 21st Century Fox an opportunity also to make a renewed bid for rival Time Warner.
BSkyB said it planned to acquire the rest of Sky Deutschland from the German group's minority shareholders, creating a pan-European TV giant in deals costing the British group a total of up to £7.0 billion (€8.8 billion) in cash.
"The enlarged company will be a world-class multinational pay TV provider that serves 20 million customers and brings together the leading pay TV businesses in three of Europe's four biggest markets," BSkyB said in the statement.
James Murdoch, son of Rupert and the co-chief operating officer at 21st Century Fox, said "a combination of the European Skys would create enormous benefits for the combined business and for our shareholders".
As part of the tie-up, BSkyB said it would transfer its minority stake in National Geographic Channel to 21st Century Fox at a value of £382 million (€481.6 billion).
"By creating the new Sky, we will be able to use our collective strengths and expertise to serve customers better, grow faster and enhance returns," BSkyB chief executive Jeremy Darroch said in Friday's statement.
Battling stiff competition
BSkyB is facing intense competition from British telecoms firm BT, which launched its own pay-TV sports channels last year showing English Premier League football.
And BT outgunned BSkyB last November to secure exclusive rights to televise across Britain all of Europe's Champions League and Europa League football matches for three seasons from 2015.
BSkyB, which sells also phone and Internet services to its customers, said on Friday that its annual net profit dropped 11.6 percent to £865 million (€1.09 billion) in the 12 months to June, hit in part by costs linked to broadcasting rights to the Premier League, which last season was won by Manchester City.
After the announcement, shares in BSkyB slumped 5.30 percent to 876 pence (€11) in afternoon deals on London's benchmark FTSE 100 index, which was down slightly overall.
"The weakness in the share price ... is reflective of the fact that the acquisition will represent a major challenge to execute, at a time of fierce competition and therefore potential growth erosion in Sky's domestic market," said Richard J Hunter, head of equities at Hargreaves Lansdown Stockbrokers.
"Sky is clearly taking the strategic view that Pay TV, already ingrained in the US culture, will become prevalent in Europe."
Earlier in July, 21st Century Fox revealed that it had made an unsuccessful bid for Time Warner. A successful bid would merge two of the world's biggest media-entertainment empires if allowed to proceed.
The initial offer was for $80 billion (€101 billion), a source familiar with the talks had told AFP.
Earlier this year, British mobile phone group Vodafone bought Spanish cable giant Ono for €7.2 billion, having already snapped up Kabel Deutschland, the largest cable operator in Germany, for €7.7 billion in 2013.
US giant Liberty Global took over its British rival Virgin Media last year in a deal worth €17.3 billion.
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