Argentina's first lady Cristina Fernandez de Kirchner swept to victory in the presidential vote.

She is the first woman elected to lead the country.

"We've won by a wide margin," she said.

Exit polls and early official results showed her with enough support to take a first-round victory and avoid a runoff election.

There were cheers on Sunday when Fernandez appeared on stage with husband President Nestor Kirchner, while dozens of supporters celebrated in the streets.