Hama Amadou, the main opponent to President Issoufou in Niger’s presidential election, has been denied his request for provisional release.
The former prime minister and national assembly president was arrested in November on his return to Niger from a year in exile over allegations of baby trafficking.
The news comes two days after his candidacy for presidency was accepted.
The first round of the vote is scheduled for February 21, alongside legislative polls.
Niger’s President Mahamadou Issoufou has confirmed he will seek re-election and will be facing up to 14 candidates in the poll.