Reykjavik (AFP) - The Panama Papers came back to haunt Iceland's right-wing parties Monday as they prepare to form a new government, after the candidate for prime minister admitted hiding a report on offshore accounts.

Iceland was rocked in April when the Panama Papers revealed a global tax evasion scandal that ensnared several senior politicians and triggered the resignation of former prime minister Sigmundur David Gunnlaugsson, with snap elections held on October 29.

The centre-right government in power at the time called for an inquiry into tax havens. It presented its conclusions on Friday, nine months after the scandal.

But on Sunday, Finance Minister Bjarni Benediktsson, whose Independence Party was the big winner in the election, admitted he had received the report's conclusions three weeks before the vote.

"This report was presented to me in the first week of October," he told public television RUV, saying he had decided not to make it public when he received it because parliament was about to break ahead of the election.

The news angered the head of the anti-establishment Pirate Party, Birgitta Jonsdottir, whose party reaped gains from a wave of popular anger with the establishment parties.

"To say, as Bjarni does now, that this would not have had any effect on the outcome of the elections is of course absurd. If the report had been presented in parliament shortly before the elections and people would have seen in black and white how much taxpayer money had passed by, it definitely would have put the matter back on the agenda," she wrote on Facebook on Monday.

The two centrist parties currently in talks to form a government with Benediktsson's Independence Party, the Reform Party and Bright Future, have yet to comment on the matter.

During the Panama Papers crisis in April, the two parties had called on voters to sanction the politicians mentioned in the Panama Papers at the polls.

According to the inquiry, the loss of tax income due to offshore accounts in Iceland amounted to between 2.8 and 6.5 billion kronor (23-54 million euros, $24-57 million, at current exchange rates) per year between 2006 and 2014.