A Nigerian tribunal has dismissed major opposition challenges to overturn President Bola Ahmed Tinubu's February election victory after a highly contested ballot.

The five members of Nigeria's presidential election tribunal on Wednesday dismissed all claims made by Labour Party candidate Peter Obi and Peoples Democratic Party (PDP) candidate Atiku Abubakar to cancel the election, alleging irregularities.

"This petition is hereby declared unmeritorious," said Judge Haruna Tsammani in the Abuja courtroom after reading out the detailed ruling on Obi's petition that alleged fraud, charged the electoral authority broke the law and claimed that Tinubu was not eligible to run.

Abubakar's petition laid out similar complaints against the 25 February election results.

Tsammani said Atiku's allegations of vote fraud and were "so lame" and dismissed his argument that Tinubu was not qualified to run for president.

Atiku and Obi can appeal to the country's Supreme Court, which has never ruled to overturn a Nigerian presidential election since the country returned to democracy from military rule in 1999.

In a statement from India where he attending the G20 summit, Tinubu, who was sworn in in May, welcomed the ruling and urged his rivals and their supporters to support his government.

The election was one of the most contested in the country's modern history, partly because of Obi, a third-party candidate who credibly challenged the dominance of Tinubu's All Progressives Congress (APC) and the PDP.

During the vote, the Independent National Electoral Commission (INEC) had introduced biometric technology and IReV, a central database for uploading results in real time, to improve transparency.

The Commission acknowledged "glitches" but dismissed claims the vote was not free and fair. But critics had said the technical problems and delays had allowed opportunities for vote manipulation.