NEW YORK (Reuters) - Boston Red Sox slugger David Ortiz said taking nutritional supplements may have caused him to land on a 2003 list of Major League players who tested positive for performance-enhancing substances.

The 33-year-old Ortiz said he was "a little bit careless back in those days when I was buying supplements and vitamins over the counter."

"But I never ... use(d) steroids," he told a news conference at Yankee Stadium on Saturday before Boston's game against New York.

Ortiz and then-team mate Manny Ramirez, who helped the Boston Red Sox end an 86-year World Series title drought in 2004, tested positive for performance-enhancing drugs in 2003, The New York Times reported on July 30.

(Writing by Steve Ginsburg in Washington; Editing by Sonia Oxley)