Nigerian pipeline carrying Bonny Light shut as precaution

(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 a precautionary measure after a fire was seen, a spokesman for the Shell Petroleum Development Company of Nigeria Ltd (SPDC) said on Monday.

It was not yet clear whether export supplies will be subject to force majeure, according to Shell (LSE: RDSB.L - news) .

The SPDC spokesman said a fire was spotted on the "right of way" on the Trans Niger Pipeline (TNP) at Gio (Taiwan OTC: 3610.TWO - news) in Ogoni land, one of two pipelines that export Bonny Light crude oil.

The line is also the right of way for a Bonny-refinery pipeline belonging to the Petroleum Products Marketing Company (PPMC), a subsidiary of state-owned Nigerian National Petroleum Corporation (NNPC).

"A joint investigation visit will determine the cause and impact of the fire," the Shell spokesman said.

Witnesses reported eruptions at two points along the pipeline and said a fierce fire forced locals to evacuate.

"The fire is huge and still raging when I left," said Kentebe Ibiaridor, a project officer with a local environmental rights group. "We do not know the cause of fire yet, whether it is sabotage or system failure.

Bonny Light crude is also exported via the Nembe Creek Trunk Line.

On Saturday, the Niger Delta Avengers, a group that has claimed responsibility for a string of attacks on Nigerian oil infrastructure this year, said it had struck a Bonny Light pipeline, ending several weeks of calm under a ceasefire with the government.

A spokesman for the militants said in an emailed statement that 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 Yenagoa and Anamesere Igboeroteonwu in Onitsha; editing by David Clarke)