But Gnassingbe's People's Rally (RPT), Togo's ruling party, dismissed the claim as "unacceptable", the AFP news agency reported.
"We demand that this candidate exercise control to preserve the serenity that has been prevailing till now," Solitoki Esso, the secretary general of the ruling party, said.
Call for calm
Election officials sorted through the ballots on Friday, after calling on citizens to remain calm while results from Thursday's poll are tallied.
In a statement broadcast on state television, the independent electoral commission urged candidates and voters to "exercise patience and serenity while the commission makes every effort to centralize the results from various polling stations", the Associated Press news agency reported.
It said the commission will release provisional results by Saturday.
The race pitted six opposition candidates against the incumbent, Faure Gnassingbe, 43, who came to power in 2005 after the death of his father, General Gnassingbe Eyadema, whose dictatorial rule lasted 38 years.
Voters in the capital Lome had characterised the poll as an attempt by "the palm tree" to "uproot the maize".
The maize is the emblem of the RPT, and the palm tree is the symbol of the UFC, the main party of the divided opposition.
Gnassingbe, a former mines minister and financial adviser under his father, is seeking a second-term mandate but the opposition dismisses him as a candidate of "a system" that froze development over the past 43 years.
Gnassingbe vowed that this poll will raise Togo to new heights, on the basis of "a state of law".
With the main opposition party [the UFC] expressing concern over possible electoral fraud, forty international observers were deployed by the African Union, 130 by the European Union and 150 civilians and 146 soldiers by the Economic Community of West African States to oversee the elections.
The commission had vowed to stage a free and fair poll, devoid of violence, and there were no reports of of any incidents during the polling, police said.
Election officials were trying to prevent a situation similar to Togo's presidential election in 2005 when hundreds of people died in post-election violence.
The violence that followed the disputed vote in 2005 left up to 800 dead according to various sources, but the UN put the toll at 400 to 500 deaths.
Yet parliamentary elections two years later were peaceful, raising hopes of an end to Togo's long history of political violence and leading to the restoration of foreign aid.