NEW YORK (Reuters) - Philadelphia Energy Solutions has been seen selling biofuel credits, called Renewable Identification Numbers (RINs), in the months leading up to filing for Chapter 11 bankruptcy protection, market sources said.

PES said on Monday that the company filed for bankruptcy, its second such filing in less than two years, after a fire last month prompted it to close the largest refinery on the U.S. East Coast.

Market sources said the company, which typically buys RINs to comply with federal biofuel mandates, was seen selling the credits earlier this year as well as after they announced on June 26 that they would shut the 335,000 barrel-per-day complex without a planned restart.

PES declined to comment on internal business matters.