NEW YORK (Reuters) - The number of baseball players born outside the United States and featured on Major League Baseball opening day rosters this week slipped to its lowest level in four years, the league said on Tuesday.

As MLB's 30 teams begin their 2010 season this week, 27.7 percent of players, or 231 of the 833 listed on opening day rosters, were born outside the United States, the league said in a statement.

That is down from last season when 28 percent of players, or 229 players of the 818, were born outside the United States. It also marks the lowest level since 2006 when 27.4 percent of 813 players were foreign-born.

The all-time high came in 2005 when 29.2 percent were foreign born.

The Dominican Republic leads the Major Leagues with 86 players featured on opening day rosters and born outside the United States, followed by 58 players from Venezuela, which is that country's highest ever total.

The New York Mets lead all teams with 18 foreign-born players from seven different countries and territories outside the United States.

The Chicago Cubs, Colorado Rockies, Los Angeles Angels of Anaheim, Los Angeles Dodgers and Texas Rangers each have 10 players on their rosters born outside the United States.

There are 21 players from Puerto Rico listed on opening day rosters, followed by Japan (14), Canada (13), Mexico (12), Cuba (7), Panama (5), Australia (4), Taiwan (3) and Colombia, Korea, Nicaragua and the island territory of Curacao each with two.

(Writing by Frank Pingue in Toronto; editing by Pritha Sarkar)