Zimbabwean President Robert Mugabe's party has asked electoral officials to delay the results of the presidential poll and to recount votes, reports say.
The state-run Sunday Mail newspaper said the governing Zanu-PF party requested a recount because there had been "errors and miscalculations".
The paper also quoted a senior minister as saying it had rejected an opposition approach to form a unity government.
On Saturday, the opposition accused President Mugabe of "preparing a war".
Movement for Democratic Change (MDC) leader Morgan Tsvangirai warned that "militants are being rehabilitated" and troops deployed ahead of a possible second round run-off in the presidential poll, which he insists he won.
Mr Tsvangirai also claimed that the country's central bank was printing money "for the finance of violence".
He called on Mr Mugabe to enter a dialogue to prepare for a peaceful transition.
Meanwhile, the High Court is due to hear today Sunday, an MDC petition demanding that the Zimbabwe Electoral Commission (ZEC) declare a winner.
In its article on its website, the Sunday Mail said Zanu-PF had written to the ZEC asking it to review the counting of votes. The letter said anomalies had been detected in a number of constituencies, the paper reported.
"Consequent to the anomalies, the party has also requested that the commission defer the announcement of the presidential election result," it added.
According to papers submitted to the ZEC by Zanu-PF, the number of votes for Mr Mugabe recorded at a number of polling stations were reduced before being sent on to electoral officials.
Some ZEC officials working in the Midlands constituencies of Mberengwa East, West, North and South had since been arrested, the Sunday Mail said.
"As will soon become apparent, the constituency elections officer and his team committed errors of miscounting that are so glaring as to prejudice not just our clients' candidate but also his co-contestants," Zanu-PF's letter said, according to the Sunday Mail.
"There can be no doubt that the entire results of the presidential election in Mberengwa's four constituencies are grossly irregular and cannot stand up to scrutiny," it added.
In a separate article, the Sunday Mail quoted Justice Minister Patrick Chinamasa as saying the Zanu-PF had rejected an offer from Mr Tsvangirai to form a national unity government.
The Zanu-PF complaint came hours after the ZEC declared the final results of last week's Senate election. It said Mr Mugabe's party had won 30 seats, with the combined opposition taking the same number.
In the lower house, opposition parties took 109 seats, while Zanu-PF won just 97 - the first time it has failed to win a majority since independence from the UK in 1980.