ABUJA, Nigeria (AP) — An appeals court in Nigeria was to rule Wednesday on whether President Bola Tinubu's election victory in February was legitimate — a highly anticipated decision that has put Africa's most populous country on edge.

The election results were challenged by the opposition, which claimed that Tinubu, who has now been in office for 100 days, was not qualified to run because he, among other things, allegedly did not have a required high school certificate or a college or university diploma.

Security was tight in the Nigerian capital of Abuja, where five judges at the Court of Appeal were to hand down their ruling. Under the law, the tribunal is empowered to either uphold Tinubu's election win, declare someone else the winner, annul the vote or order a new election. Its decision can be appealed before Nigeria's Supreme Court.

The opposition has hinted at possible protests if the court rules in favor of Tinubu.

Analysts say Wednesday's ruling will be significant for this country of more than 210 million people. If the February presidential election is annulled, it would be a first in Nigeria's history. If upheld, the ruling would boost the role of the election commission, which the opposition claims violated the law. It could also open a path for the body to decide on its own when and how election results are announced in the future.

Under the law, a presidential election can be annulled only on evidence that the national electoral body did not follow the law and acted in ways that could have changed the result.

On Tuesday, police in Abuja issued a statement warning citizens “to be cautious in their actions and statements,” saying security forces would not "condone activities capable of inciting violence or causing a descent into anarchy.”

The 71-year-old Tinubu won the election with less than 50% of the vote, also a first in Nigeria’s history. The election results are being contested by three opposition candidates, including Atiku Abubakar, Nigeria's former vice president who came in second, and Peter Obi of the Labor Party, who finished third.

Both opposition candidates filed separate petitions arguing that Tinubu was not qualified to become president and claiming the electoral commission did not follow due process in announcing the winner. The delays in uploading and announcing election results could have given room for the ballots to be tampered with, critics say.

The opposition has also alleged that Tinubu was indicted for drug trafficking in the United States, that he is a citizen of Guinea which disqualifies him to run in presidential elections in Nigeria, and that his academic qualifications were forged.

Tinubu has denied all the allegations. Since taking office, he has introduced measures that he said would reform the ailing economy but that have over the past months further squeezed millions of poor and hungry Nigerians.

On Tuesday, Nigeria Labor Congress workers launched a two-day “warning strike” to protest the growing cost of living due to the removal of gas subsidies, threatening to “shut down” Africa’s largest economy if their demands for improved welfare are not met. It was their second strike in over a month.

Since Nigeria returned to democracy in 1999, all presidential elections but one have been contested in court. None has been overturned.