Financial guru Warren Buffett has backed a campaign group aiming to improve gender balance at all levels of US companies.

The chairman and chief executive officer (CEO) of Berkshire Hathaway lent his support to the 30% Club, which has launched in the United States.

The group will focus on improving representation of women at all levels of US organisations, with a near-term focus on female representation in senior leadership.

"There is no better time to focus on developing a pipeline of female talent in US organisations," said Helena Morrissey, CEO of Newton Investment Management and founder of the 30% Club.

"There are many excellent company efforts and networking groups addressing this issue, but we still need to do more to elevate the visible commitment of senior business leaders, who are mostly men."

The organisation first launched in the UK in 2010 with a goal of 30% women on FTSE-100 boards by the end of 2015.

There are now 92 members of the 30% Club in the UK and the FTSE-100 has moved from 12.5% women directors in 2010 to 20.8% as of March 2014.

Club supporters in the UK have focused on creating better gender balance by targeting talent management practices, executive search firms, shareholders, schools and universities and others.

Peter Grauer, chairman of Bloomberg L.P., will serve as founding US chairman of the organisation and the group has 24 founding supporters, including Buffett and Larry Fink, the CEO of BlackRock.