* Director says refinery stoppage was planned
* Gabon oil sector strike enters fourth day
* Union says it has opened negotiations with govt (Adds details on strike, change dateline)
By Jean Rovys Dabany
LIBREVILLE, March 13 (Reuters) - Production at Gabon's soleoil refinery has been halted for three-weeks of plannedmaintenance, its director said on Wednesday, as a strike byGabonese oil sector workers entered its fourth day.
A union member had told Reuters earlier that work hadstopped at the 21,000 barrels-per-day refinery due to a fire andthe effects of the strike.
But Pierre Reteno Ndiaye, Sogara's director general, toldReuters by phone from Gabon's Port Gentil oil hub that thestrike was not the cause and the fire did not do any extensivedamage to the plant.
"The strike is not having an impact," Ndiaye said. "Therewas a minor fire yesterday following a spillage but that wasduring the planned three-week maintenance, and it was quicklyput out."
Ndiaye said maintenance work, which began on Friday, willboost capacity at the refinery co-owned by the Gabonesegovernment, France's Total, Portofino AssetsCorporation, Petro Gabon and Eni SpA subsidiary Agip.
Members of Gabon's powerful ONEP oil workers' union began anopen-ended strike on Saturday to demand the application of a2010 agreement, signed by the government, guaranteeing betterlabour terms and greater use of Gabonese staff.
ONEP's Secretary-General Guy-Roger Aurat Reteno, said onWednesday that the strike had paralysed about 60 percent ofGabon's roughly 240,000 bpd petroleum sector.
The industry is dominated by Total and Royal Dutch Shell, with juniors Tullow, Perenco, Addax, China'sSinopec, and Maurel & Prom among the other players.
A spokesman for Total said on Wednesday output from theiroperations in Gabon had not been affected.
Reteno said the union had open negotiations with thegovernment.
"We decided to start negotiations since yesterday afternoonbecause we realised that the last strike in 2010 cost thecountry about 60 billion CFA francs ($119.10 million) and wedon't want this to happen again," Reteno said.
Oil revenues contribute around 60 percent of the statebudget in Central African nation of about 1.5 million people.($1 = 503.7690 CFA francs) (Additional reporting and writing by Bate Felix; Editing byRichard Valdmanis)
