US Federal Reserve chief Janet Yellen has signalled that a rise in US interest rates is unlikely in the near future.

Ms Yellen said that while the US economy was improving, the US employment situation was still fragile.

"Too many Americans remain unemployed or underemployed... wage growth is still sluggish," she said.

As Michelle Fleury reports, her comments helped propel US shares to fresh highs - the Dow and S&P 500 both closed at records.