NEW YORK (REUTERS) - The Dallas Cowboys of Americn football have unseated Spanish football's Real Madrid as the world's most valuable sports franchise, according to a Forbes poll released on Monday.

A new broadcasting deals helped boost the valuee of the average team in the National Football League (NFL) in the United States by 38 per cent from last year, the magazine said, and remain the NFL's most valuable team for a ninth consecutive year, Forbes said in a statement.

The Cowboys, which have not won a Super Bowl title in 20 years, are valued at US$4 billion (S5.62 billion), a 25 per cent jump from last year, compared to US$3.25 billion for Real Madrid.

Rounding out the top five are the Super Bowl champion New England Patriots and New York Yankees baseball team, both valued at US$3.2 billion, and Real Madrid rivals, Barcelona, at US$3.16 billion.

By comparison, the most valuable English Premier League team is Manchester United. Forbes put its worth at US $3.1 billion, with US$703m in annual revenue and a 10-year, US$1.1 bn sponsorship deal with Adidas.

The average NFL team in the US is now worth US$2 billion the highest value in the 18 years Forbes has been tracking professional football team values.

According to Forbes,what the most valuable teams on the list have in common is a presence in large markets and stadiums which provide them with more premium seating and sponsorship revenue than other teams generate.