Several black men who were contracted to work at the Sunoco refinery in Philadelphia were forced to clean up racial slurs written about them on bathroom walls, the men claim in a federal civil rights lawsuit.

Along with racial epithets, the men also claim in the suit filed Wednesday that there were nooses left around the workplace on several occasions.

The six plaintiffs, led by Kenneth Hall, 40, of Philadelphia, were all employees of Advanced Speciality Contractors, of Aston, which was contracted to work on a project at the Sunoco refinery on Passyunk Avenue near 61st Street in Southwest Philadelphia, the suit said.

White employees of other companies subcontracted for the project, including Burns & McDonnell of Kansas City, Mo. and Riggs Distler of Cherry Hill, N.J., harassed the men because of their race, the suit says.

Among the harassment alleged is that white employees hung nooses on pipe racks around the refinery and on the rear view mirror of the truck one of the plaintiffs used.

Along with the nooses, the suit claims racial slurs were written daily on bathroom and port-a-potty walls including "whites only, no n - - - - - - allowed" and "all n - - - - - - should go back into slavery."

The plaintiffs, who performed various jobs around the refinery including janitorial work and general labor, were forced to clean and paint over the slurs, according to their attorney, Kevin Lovitz.

"You are being made to clean up what is the most heinous racial conduct you could imagine - against yourself!" Lovitz said. "And they couldn't stop it."

He said the harassment mostly occurred in 2008 and 2009 and coincided with President Obama's campaign and election, which he said provoked negativity among the refinery's white workers.

"That is the backdrop of why these things may have been so focused at the time," he said. "There was a lot of negativity with regard to the election on a racial level."

According to the suit, Hall and the other black employees complained repeatedly to managers at Sunoco, Advanced Specialty, Burns & McDonnell and Riggs Distler but nothing was done.

Riggs Distler President Leo Sniger said he was aware of the allegations from Hall, but that the company had nothing in their records that showed discrimination complaints had been filed with the company.

"We take that stuff pretty seriously when something like that happens," he said. "It normally comes right to my desk, and though it very seldom does, we send out a full team to investigate it immediately."

A phone message left at the local office of Burns & McDonnell was not returned' nor was an e-mail request for comment sent to the company's corporate communications manager.

A Sunoco spokesman declined to comment on the case because it involved pending litigation, as did an employee at Advanced Specialty.

Lovitz said the harassment came to a head on April 23, 2009, when a white employee of Riggs Distler accused Hall of washing a truck with chemicals that were making him sick.

When Hall told the man he was using only water to wash the truck, he allegedly approached Hall with fists drawn, called him a "dumb n - - - - - " and the two began to fight, according to the suit.

A Riggs Distler supervisor who was present at the time didn't stop the fight, the suit said.

Both Hall and the white man he was fighting with were fired as a result of the altercation, Lovitz said.