Inauguration: Barack Obama is sworn in for second term

Barack Obama has taken the oath of office in Washington DC to inaugurate his second term as US president, before hundreds of thousands of spectators.

Mr Obama, 51, who is the 44th president of the US, was sworn in by Chief Justice John Roberts.

Monday's inaugural festivities in the US capital include black-tie balls, a parade and musical performances.

In his inaugural address, the Democratic president is now laying out his vision for the next four years.

He was formally sworn in at a small White House ceremony on Sunday - the US Constitution dictates presidential terms begin on 20 January.

In the famous Blue Room with his wife and daughters, the 44th president rested his hand on a Bible that was used for many years by Michelle Obama's family, as Justice Roberts administered the oath of office.

In his inaugural address, Mr Obama is not expected to preview his policy agenda on Monday. He will address that in next month's State of the Union speech, asking bitterly divided lawmakers to come together and reduce gun violence, overhaul the immigration system and reduce the yawning federal budget deficit.

Four years ago, Mr Obama repeated the oath privately to make sure all constitutional obligations were met after Justice Roberts tripped over the words in the public ceremony.

Officials estimate about 700,000 people were to attend the inauguration, down significantly from 2009, when about 1.8 million people witnessed Mr Obama be sworn in as America's first black president.

About 260,000 people attended George W Bush's second inauguration ceremony in 2005, with an additional 150,000 lining the parade route, officials said.