Update | Yellen says Fed on track for US rate hike in 2015

Federal Reserve Chair Janet Yellen received medical attention on Thursday after coughing, pausing and struggling to finish a speech in which she said the U.S. central bank was on track to raise interest rates for the first time in nearly a decade.

The 69-year-old Fed chief, who had been speaking for nearly an hour before a packed university auditorium here, appeared to lose her place in reading the last few lines of her speech on inflation. She abruptly said: "Let me stop there."

As head of the world’s most powerful central bank, Yellen plays a major role in the global economy and has been at the center of speculation over when the Fed would finally raise rates after being at near zero for almost seven years now, a move that would reverberate through financial markets worldwide.

The frightening few moments, in which Yellen appeared to lose her concentration a few times in a speech at the University of Massachusetts, Amherst, came in her first public comments a week after she explained the Fed’s decision to delay the much-anticipated policy tightening.

"Chair Yellen felt dehydrated at the end of a long speech under bright lights," Fed spokeswoman Michelle Smith said in an email. "As a precaution, she was seen by (emergency medical) staff on site at UMass Amherst. She felt fine afterwards and has continued with her schedule Thursday evening."

A university spokesman said she was attending a dinner event as planned.