The chairman of the Consumer Product Safety Commission has flatly denied allegations made by a consumer advocacy group that he provided internal agency information to companies targeted by CPSC investigations for suspected safety violations.

In a letter to Sen. John Danforth (R-Mo.) last week, CPSC Chairman Terrence M. Scanlon said that there was "no substance to the allegation" made by Joan Claybrook, president of Public Citizen.

Public Citizen, a national public-interest group founded by Ralph Nader, called on the Senate Commerce, Science and Transportation Committee two weeks ago to initiate a federal investigation into the activities of Scanlon, who was nominated by President Reagan in December in a recess appointment.

Along with several allegations about what Claybrook called Scanlon's "anti-regulatory posture," she charged that he may have used government facilities to promote the anti-abortion movement.

Scanlon said, in his letter, that "Claybrook's statement to the committee contains allegations and occasional innuendo which are entirely devoid of facts."

Sen. Robert Kasten (R-Wis.), who chairs the committee's consumer subcommittee, was holding confirmation hearings on both the nomination of Scanlon and the nomination of Anne Graham to the open seat on the commission when Claybrook made her charges.

Kasten asked Scanlon, who left the Senate hearing before Claybrook testified, to submit a response to all of the charges.

Scanlon's letter to Danforth did not address the charge that he used government facilities to promote the Right to Life movement, except to state that " . . . Ms. Claybrook begins and concludes her testimony with remarkably broad and unfounded allegations. She believes that I am not fit to be a regulator of consumer products and that the staff is now 'uninformed, uninvolved and afraid to state the facts.' She claims a misuse of government facilities based on allegations 'inside the commission.' "

"Mr. Scanlon's response to the commmittee concentrates mostly on my critique of his anti-regulatory posture," Claybrook said yesterday. "I believe the main concern of the committee focuses on my concern about misuse of government facilities and prior communications with regulating companies."

Claybrook submitted additional information to the committee yesterday that she said backed up her charges against Scanlon, but neither she nor the committee would release her letter.

Committee staffers said that Scanlon's response, along with the additional information from Claybrook, would have to be evaluated before any decision could be made regarding a federal investigation. The committee has not scheduled a vote on the nominations.

Scanlon, 46, vigorously supports the use of voluntary standards over mandatory regulations for industry. He has been a member of the CPSC since March 1983 and formerly served in the Commerce Department. Graham, 36, is assistant secretary of the Education Department for legislation and public affairs.