A leading opposition figure in Niger who returned from self-imposed exile last week was jailed on Monday to serve out the rest of his time for a conviction of baby smuggling, his family told AFP.Hama Amadou, 69, who had flown home last Thursday after his mother died, "was incarcerated early today in Filingue," 180km north of the capital Niamey, a relative said."He went to court voluntarily and was taken to prison."A former premier and parliamentary speaker, Amadou has been nicknamed "the Phoenix" for his political comebacks.In November 2015, he was arrested on his return from abroad and charged with baby-trafficking - a case that supporters said was trumped-up.He campaigned for the March 2016 presidential elections from behind bars, gaining 17.7% of first-round votes behind President Mahamadou Issoufou, who won 48.4 percent.He was released on medical grounds four days before the runoff ballot, flew to France and remained abroad until his return last week.In March 2017, 20 people, including Amadou, were convicted in the case, which allegedly entailed smuggling babies from Nigeria via Benin for wealthy couples in Niger. He was given a 12-month sentence in absentia, of which eight months have still to be served, after time spent in prison is taken into account. One of his wives was also sentenced.In August this year, Amadou was named by the Nigerien Democratic Movement (Moden), the country's main opposition party, to be its candidate in the next presidential election, due in December 2020.Issoufou, a former prime minister, has been president since 2011.His country has a history of political volatility and has only had a multi-party democracy since 1990.The impoverished Sahel state has one of the lowest rates of development in the world. Three-quarters of the population live on less than $2 a day.Amadou, after visiting his mother's grave, spent the weekend greeting a large number of visitors to his home, his family said.They included supporters but also members of the Nigerien government and civil society, who came to express their condolence for his loss.He even spoke by phone with Issoufou, one of whose wives, Malika Issoufou, went to his home, said a relative.Uncertain future Analysts said that Amadou's political future remained unclear.An expert on constitutional law, Amadou Boubacar, said that even if he served the entirety of his sentence before the December 2020 election, he would still be legally ineligible for a tilt at the presidency."Under the law, anyone sentenced to a prison term equal to or greater than one year is not eligible," Boubacar said."Even a presidential pardon is not enough. There would have to be a law amnestying baby-smuggling in order to annul the sentence."In that context, Amadou's future could largely depend on a "political dialogue" promised last month by Prime Minister Brigi Rafini, Boubacar said.A push for reconciliation could favour concessions for Amadou, who since his return has notably called for the easing of tensions.Officially, the "dialogue" aims at "calming the political climate" ahead of the presidential ballot, with discussions on future elections, Niger's electoral commission and access to the media.Rafini said an "assembly" of 30 people from Niger's political parties, plus five from trade unions and three from civil society, would be named shortly to conduct the month-long forum.Representatives from the UN, the European Union, a non-partisan American NGO called the National Democratic Institute will take part, as will local religious leaders and traditional chiefs.