Fijian Prime Minister Frank Bainimarama and his FijiFirst Party have been returned to government with a tiny majority in an election that was delayed by intense storms, local media reported Sunday.

The Fiji Times newspaper reported that FijiFirst won 50.2 per cent of the vote, giving Bainimarama 27 of the 51 seats in the Pacific nation's parliament for the next four years.

The result represented a drop in support for Bainimarama, who won the 2014 election with 60 per cent of the vote.

However, Bainimarama said in a victory statement to the Fiji Broadcasting Corporation that Fijians had "emphatically voted" to support his government.

The election was held last Wednesday, but heavy rain caused some parts of Fiji to delay voting until Saturday.

Earlier on Sunday, leaders of the four opposition parties held a joint press conference in Suva to say they were concerned there appeared to be discrepancies in official figures being released by the election authority, the Fiji Times reported.

Opposition leader Sitiveni Rabuka of the Social Democratic Liberal Party, which won almost 40 per cent of the vote, told the Australian national broadcaster ABC that he may call for another election.

"I'm not fully satisfied, that's why we brought up concerns with the multinational observers," the ABC reported him as saying. "We may be calling for another one, because there are still issues we're not totally satisfied with."

Both Bainimarama and Rabuka have led military coups against the government in the past.

This was the second free election since Bainimarama overthrew the government in 2006 when he was head of the Fijian military.

Rabuka was an army colonel in 1987 when he instigated two military coups against the elected government. He stayed in office for much of the 1990s.

Australia's Foreign Minister Marise Payne released a statement congratulating Bainimarama on his re-election and said the Multinational Observer Group had declared the electoral process transparent and credible.