NIAMEY, March 29 (Reuters) - Niger opposition leader Hama Amadou, jailed since November on baby trafficking charges, was granted a provisional release by a court on Tuesday a week after losing a presidential run-off election, his lawyer said.

Amadou, a former speaker of parliament, has denied the charges, saying they were part of a strategy to sideline him politically. He is currently in France, where he was flown for medical reasons just days before the March 20 second-round vote.

"Niamey's court of appeals agreed to our request and today it ordered Hama Amadou's provisional release," said lawyer Mossi Boubacar.

President Mahamadou Issoufou won a second term with 92.5 percent of the vote, according to official results announced last week.

Held in a prison several hours from the capital Niamey and suffering from poor health, Amadou was unable to campaign and an opposition coalition backing him called for a boycott, easing the way for Issoufou's victory.

"The court should have freed him so that he could be on equal footing with Issoufou during the elections. It didn't. Hama is innocent and this case is a plot to push him out of political life," said opposition spokesman Ousseini Salatou.

Police began making arrests in June 2014 in an investigation into the alleged trafficking of newborn babies into the West African uranium-producing country from neighbouring Nigeria.

A number of members of Niger's political elite, including Amadou's wife, were charged but later granted provisional release after spending up to six months in detention.

Amadou fled Niger amid the wave of arrests. He returned in November and was arrested.

Issoufou has positioned himself as an ally of Western nations in the fight against Islamist insurgents in the arid Sahel region. Critics, however, say he has become increasingly authoritarian and clamped down on dissent.

(Reporting by Abdoulaye Massalaki; Writing by Joe Bavier; Editing by Mark Heinrich)