A far-right party in Sweden has won seats in parliament for the first time, denying the governing centre-right coalition an overall majority.
The anti-immigration Sweden Democrats have won 20 of the 349 seats in the country's single assembly, following Sunday's general election.
The alliance, led by centre-right Prime Minister Fredrik Reinfeldt, fell short of a clear victory with 172 seats.
Mr Reinfeldt says he will seek the support of the opposition Green Party.
The Greens are currently allied with the centre-left Social Democrats.
Green Party co-chair Maria Wetterstrand said the opposition bloc - which won 157 seats - remained united.
Mr Reinfeldt also did not rule out working with the Social Democrats.
"On many questions there is a possibility for broader co-operation," he told reporters. "We have to see how the Social Democrats define their road ahead."
However the prime minister reiterated that his four-party Alliance for Sweden would not form a coalition with the far-right.
"I have been clear on how we will handle this uncertain situation," he said. "We will not co-operate, or become dependent on, the Sweden Democrats".
Sweden Democrats leader Jimmie Akesson said his party would use the opportunity to make itself heard, as it had not been invited to official debates during the campaign.
"We have in many ways been treated as anything but a political party in this election," he said.
"Even so, today we stand here with a fantastic result. The situation is a bit uncertain just now, but we have four years ahead of us to speak out on the issues that matter to us and influence Swedish politics."
BBC regional reporter Damien McGuinness said the success of the far right has shocked many voters in Sweden.
Winning 20 seats in parliament, the Sweden Democrats have obviously touched a nerve, he adds.
The party appears to have tapped into voter dissatisfaction over immigration, says our correspondent, with the result undermining the image of Sweden as a tolerant and open-minded country.
Mr Reinfeldt could remain in office with a minority government - which although not that unusual in Sweden, would mean he would have to win over other parties to push through bills.
Immigrants make up 14% of the country's population of 9.4 million.
The Social Democrats have ruled Sweden for 65 of the past 78 years, and are credited with setting up the country's generous welfare state.
Conceding defeat on Sunday, party leader Mona Sahlin said they had not been able to win back voters' confidence.
"The Alliance is the largest majority. It is now up to Fredrick Reinfeldt how he plans to rule Sweden without letting the Sweden Democrats get political influence."