By Simon Evans

(Reuters) - Almost twice as many Americans are watching soccer's European Championship compared to four years ago according to data released by tournament broadcaster ESPN.

The 24 games in the group stage of Euro 2012 averaged just over one million viewers compared to 552,000 for Euro 2008 - the latest sign of the impressive growth of interest in international soccer in the U.S.

The most-watched match in the group stage was the 1-1 draw between Spain and Italy on Sunday, June 10 which pulled in an average audience of 2.113 million viewers, bigger than for any game four years ago except the final.

The quarter-finals begin on Thursday with the Czech Republic v Portugal but ESPN will hope for their biggest numbers so far at the weekend when Spain face France and England take on Italy.

The games from the tournament staged in Poland and Ukraine are being broadcast during the afternoon on the U.S. East Coast and the biggest audiences have been in New York and the Miami-Fort Lauderdale area.

ESPN said figures for their digital and Spanish-language products had also risen sharply.

The network's coverage of the World Cup two years ago set new highs including a 15.5 million audience for the final between Spain and the Netherlands in South Africa.

The U.S. has traditionally been one of the weakest markets for international soccer but the game is increasingly popular among a young demographic and in the growing Hispanic community.

(Reporting By Simon Evans; Editing by Ken Ferris)