* Gbagbo party accuses govt of unilaterally fixing elections date
* Polls seen as last chance for party to rejoin political process
ABIDJAN, Feb 15 (Reuters) - The party of Ivory Coast ex-President Laurent Gbagbo threatened on Friday to boycott April local elections, undermining efforts to bring his supporters back into the political mainstream after their defeat in a brief 2011 civil war.
Gbagbo is currently awaiting trial in The Hague charged with crimes against humanity committed during the 2011 civil war sparked by his refusal to accept the election victory of rival Alassane Ouattara.
Gbagbo won 46 percent of votes in the 2010 runoff that sparked the violence, and his FPI party boycotted legislative polls in late 2011. Analysts see the local and regional elections as the last chance to reintegrate Ivorian political institutions and warn another boycott would further marginalise the former president's still numerous supporters.
The government of Ouattara, now president, on Wednesday announced the twice-delayed polls will be held on April 21.
"This is a reaction to the information given by the government two days ago," said Sylvain Miaka Ouretto, the FPI's interim president. "If the current conditions remain unchanged, we are not prepared to participate in the elections."
Most of the FPI's top leadership were either killed in the 2011 fighting, are in prison in Ivory Coast, or live in exile.
Gbagbo claimed he was leading the resistance against what he claimed was a foreign-backed northern rebellion. Ouattara meanwhile saw himself as the champion of excluded northerners, who suffered under Gbagbo's government.
Gbagbo's party, which had repeatedly snubbed previous overtures by the government to reintegrate the country's political process, entered talks with the government last month.
"We are leaving the door open. We are in negotiations with the government, and we hope to reach a point where we will be able to go back on this decision," Ouretto said.
He said the party was demanding a general amnesty for its members, the disarmament of irregular pro-Ouattara forces, and the reconstitution of the elections commission, which it claims is dominated by the president's allies.
A spokesman for the government rejected the possibility of a further postponement, saying that every effort had been made to ensure that all parties had the opportunity to participate.
"If they don't participate, it's something that is regrettable," Bruno Kone said. "But when they continue to demand preconditions that are impossible to satisfy, then that means that the FPI does not want to go to elections." (Reporting by Joe Bavier; Editing by Jon Hemming)