The investigation has been under way since January and a federal grand jury has been convened to consider price-fixing allegations against DuPont Co., The Sherwin-Williams Co., PPG Industries Inc., BASF AG, and Akzo Nobel. Spokesmen for the companies have confirmed that the investigation is under way, but said they have no reason to believe any laws were violated. The spokesmen said the companies are cooperating with authorities involved in the probe.

Published reports said the companies are alleged to have met in Europe five years ago and conspired to fix wholesale prices in the United States.

A spokesman for PPG said the company is aware of the federal probe, and said company representatives have met with antitrust officials. “We indicated we would cooperate,” said John Ruch, the spokesman. “We also did our own internal investigation, and found nothing that would indicate PPG people did anything wrong.”

David Elliott, a spokesman for BASF, confirmed that the company was subpoenaed by the Justice Department in January in connection with “possible violations of antitrust laws in the automotive-refinish industry.” He said the company has “no further details regarding the nature or scope of this investigation,” but added that “BASF has no reason to believe that it has violated any laws. We are cooperating fully with the Department of Justice under terms of the subpoena.” Elliott said that “because this is under investigation, we have no further comment. But we want to emphasize we have no reason to believe we violated any laws.”

Conway G. Ivy, a spokesman for Sherwin-Williams, also confirmed that the company received a subpoena, which he defined as an “information request.” He said the company has been “responding and cooperating with the Department of Justice,” adding that “we are unaware of any allegations of improper conduct directed at The Sherwin-Williams Co.”

Clif Webb, a spokesman for DuPont, said the company is “cooperating fully in the investigation” by the Justice Department. “Due to the confidential nature of the investigation, we are not at liberty to comment further during its pendency, but we do not expect that it will affect our normal business activities,” he said.

Representatives of Akzo Nobel were not immediately available for comment.