Marina Silva chosen to run for president in Brazil

Ms Silva replaces the late Eduardo Campos, who was killed in a plane crash last week.

She was Mr Campos's running mate and served as environment minister, BBC News reports.

She is seen as a leading challenger to President Dilma Rousseff, who's seeking re-election in the 5 October poll.

"I will give the best I have in me," said Ms Silva, 56, after the announcement, which was widely expected.

PSB President Roberto Amaral told a news conference she had been chosen unanimously.

Congressman Beto Albuquerque was named the party's new vice presidential candidate.

A much-admired figure Ms Silva will test President Rousseff's status as favourite to win October's election and make this a much more interesting process than it looked like being barely a week ago, the BBC's Wyre Davies in Rio de Janeiro says.

In the last presidential election, standing as the Green candidate, Ms Silva polled a credible 20% of the vote and is already a recognisable and much-admired figure across this continent-sized nation, our correspondent adds.

The first test of public opinion after Mr Campos's death suggested she could surpass the main opposition PSDB candidate Aecio Neves in the first round and beat current President Dilma Rousseff in the second, although both outcomes were within the poll's margin of error.

But analysts caution that, with the strong emotional reaction to last week's events, a bounce in the polls was inevitable and the picture could change substantially.