Barack Obama warns Hurricane Sandy is 'serious and big storm'

The US President has told Americans to take Hurricane Sandy "very seriously" as several states along the eastern seaboard declare emergencies.

Follow live coverage as Hurricane Sandy makes landfall

Hurricane Sandy, a mammoth storm menacing the east coast of America, is taking aim at the most densely populated US region , forcing hundreds of thousands to seek higher ground, halting public transport and closing schools, businesses and government departments.

Sandy forced President Barack Obama and Republican challenger Mitt Romney to cancel some campaign stops and fueled fears that it could disrupt early voting in the US election - encouraged by the candidates this year more than ever - before the November 6 election.

"This is a serious and big storm," Mr Obama said after a briefing at the federal government's storm response center in Washington. "We don't yet know where it's going to hit, where we're going to see the biggest impacts."