NIAMEY (Reuters) - Mahamadou Issoufou, a leading opposition figure in Niger, returned home on Friday from a trip abroad and said he was ready to face charges of money laundering, a day after a warrant was issued for his arrest.

Issoufou is one of dozens of former parliamentarians caught up in a graft investigation that critics say is a bid to muzzle opponents of President Mamadou Tandja's moves to tighten his grip on the West African nation, a major uranium producer.

"The fact that I have returned means something very simple. I have nothing to run away from," Issoufou told reporters on his return to Niger from Abuja, Nigeria, where he was in talks with West African bloc ECOWAS, which is seeking to end the crisis.

Security officials made no effort to detain Issoufou.

"I heard that they issued an international arrest warrant for me. The powers that be didn't have to go to that length. They could have simply called me to face a judge and I would have turned up," he added.

Several thousand supporters of Issoufou's Nigerien Party for Democracy and Socialism (PNDS) turned up at Niamey airport to welcome him and accompanied him home.

The case against Issoufou is the latest twist in a political crisis that has seen Tandja extend his time as president, increase his powers and remove term presidential limits. The row has deeply divided the impoverished desert state and drawn sharp criticism from donors and regional organisations.