The US ambassador to Nigeria, Stuart Symington, has warned against the release of results which are not from the Independent National Electoral Commission (INEC).
Symington also asked key candidates not to claim victory before the final announcement by INEC.
The US envoy also appealed to politicians to honour the peace accord signed to ensure successful polls.
He said the elections were “predominantly peaceful” except for violence recorded in a few places.
“I congratulate the tens of millions of Nigerians who stood patiently in long lines to vote this week and the hundreds of thousands who worked together with INEC to conduct the elections,” Symington said in a statement.
“As noted by many observer groups in their preliminary reports, this election was predominantly peaceful, and it was proof of the Nigerian people’s resolute commitment to choose their leaders.
“The peaceful achievement of millions was shadowed by the violence of a few. We extend our deepest sympathy to the families of those who lost their lives, and we urge all candidates to honor the Peace Accord they signed.
“No one should break the law by announcing results before INEC does, or break the peace by claiming victory before the results are final.
“Everyone has a common interest in showing patience as INEC collates and announces the election results.”