(Adds local witnesses, Niger Delta Avengers attack)
LONDON, Sept 26 (Reuters) - Nigeria's Trans Niger Pipeline,which carries Bonny Light crude, has been shut as aprecautionary measure after a fire was seen, a spokesman for theShell Petroleum Development Company of Nigeria Ltd (SPDC) saidon Monday.
It was not yet clear whether export supplies will be subjectto force majeure, according to Shell.
The SPDC spokesman said a fire was spotted on the "right ofway" on the Trans Niger Pipeline (TNP) at Gio in Ogoni land, oneof two pipelines that export Bonny Light crude oil.
The line is also the right of way for a Bonny-refinerypipeline belonging to the Petroleum Products Marketing Company(PPMC), a subsidiary of state-owned Nigerian National PetroleumCorporation (NNPC).
"A joint investigation visit will determine the cause andimpact of the fire," the Shell spokesman said.
Witnesses reported eruptions at two points along thepipeline and said a fierce fire forced locals to evacuate.
"The fire is huge and still raging when I left," saidKentebe Ibiaridor, a project officer with a local environmentalrights group. "We do not know the cause of fire yet, whether itis sabotage or system failure.
Bonny Light crude is also exported via the Nembe Creek TrunkLine.
On Saturday, the Niger Delta Avengers, a group that hasclaimed responsibility for a string of attacks on Nigerian oilinfrastructure this year, said it had struck a Bonny Lightpipeline, ending several weeks of calm under a ceasefire withthe government.
A spokesman for the militants said in an emailed statementthat the attack on Saturday was in the sea near Bonny island,making it unclear whether the incidents were related. (Reporting by Libby George in London, Tife Owolabi in Yenagoaand Anamesere Igboeroteonwu in Onitsha; editing by David Clarke)