A court of appeals in Niger has refused to free jailed opposition leader Hama Amadou before a run-off vote scheduled for March 20.

According to Amadou's lawyer Souley Oumarou on Monday, the appellate court said it would only deliver its verdict on conditional release for Amadou on March 28, eight days after the run-off vote.

"We asked the court to release him after securing personal guarantees from Hama Amadou or to at least release him conditionally on bail," said Oumarou.

Since November, Amadou, Niger’s former premier and parliament speaker, has been detained on alleged charges of baby-trafficking from neighboring Nigeria, a charge he has adamantly dismissed as politically motivated.

Campaigning from behind bars, he managed to gain nearly 18 percent of the vote in the first round of the presidential election held on February 21, trailing Niger’s incumbent president Mahamadou Issoufou who garnered 48 percent, failing to win outright.

In a bid to defeat Issoufou, a coalition of four parties agreed before the election to back the imprisoned candidate who came second. The coalition gained a cumulative vote of around 38 percent.

The African Union, which deployed 40 observers, has said it was generally satisfied with the organization of the vote despite delays in some areas caused by logistical glitches.

The opposition, however, accused the Nigerien government of fraud in the first round.

Prior to the poll, the opposition had anticipated a run-off vote, vowing there would be no easy victory for Issoufou.

Despite an abundance of uranium, coal and oil, Niger is one of the poorest countries in the world.

A total of 7.5 million people were eligible to vote across the country on the edge of the Sahara desert, where security is a growing concern after attacks by militants from neighboring Nigeria, Mali and Libya.