Fiji's military chief said on Friday his forces will not intervene over a national election that took place on Wednesday, after opposition leaders wrote to him raising concerns over vote-counting.
International election observers said on Friday they had not seen any significant voting irregularities, adding that an initial anomaly with the app presenting results had been rectified.
The Pacific island nation, with a population of 900,000, had a history of military coups before constitutional reform in 2013 to remove a race-based voting system that favoured indigenous Fijians over a large Indian ethnic group.
A result is expected on Sunday in a tight race between two former coup leaders, after the Fiji Elections Office conducts a final count of paper ballots.
Prime Minister Frank Bainimarama's Fiji First party was narrowly leading the final count with 38.72% of votes, ahead of Opposition leader Sitiveni Rabuka's People's Alliance party on 38.45%, at 10 p.m. on Friday, with returns from 560 of 2,071 polling stations counted.
Rabuka was taken in for questioning by police on Friday evening and later released, the People's Alliance party said in a statement.
He was shown on television leaving the Criminal Investigation Division headquarters in Suva, telling reporters he hadn't been charged.
On Thursday, Rabuka's People's Alliance had written to Republic of Fiji Military Forces Commander Ro Jone Kalouniwai expressing concerns over the election process.
Kalouniwai told TV station FBC news on Friday that the military would put its trust in the electoral process and not get involved.
"I wish to reassure the people of Fiji that the RFMF (armed forces) will not respond to Rabuka's insistence or any political party, that we intervene," Kalouniwai said in a separate interview with broadcaster RNZ Pacific.
The co-chair of a Multinational Observer Group, Australian politician Rebekha Sharkie, told reporters in Suva on Friday that counting was proceeding "in a systematic, methodical and transparent manner".
Technical problems had plagued the election office's app, used by the public to track provisional results on Wednesday evening, fuelling mistrust among opposition parties.
The app had shown a People's Alliance Party candidate leading, before it was taken offline late on Wednesday. When it went back online it showed Fiji First ahead.
The election office said mistakes had been made transferring data to the app, and it was not used to count votes.
People's Alliance and four other opposition parties on Friday launched a petition calling for an independent audit and a recount, after saying they had no confidence in the election process.
Sharkie said the election office had immediately informed the Multinational Observer Group on Wednesday evening of the anomaly with the results app, and the issue was rectified.
"Updates on final results has been slower than anticipated, due to additional quality control processes," she added.
(Reporting by Kirsty Needham; editing by John Stonestreet)