A verbal battle heated up this week between the chairman of the Consumer Product Safety Commission and the head of a consumer advocacy group over allegations that the chairman misused government property and acted improperly on behalf of companies subject to the commission's regulation.

In letters and documents released yesterday by the Senate Commerce, Science and Transportation Committee, Public Citizen President Joan Claybrook charges CPSC Chairman Terrence M. Scanlon with using his office staff and government property to conduct personal work on government time and at government expense -- allegations that Scanlon has denied in writing.

Scanlon, the highest-ranking Democrat in the Reagan administration, argued in a letter submitted to the committee Thursday that Claybrook's allegations are unsubstantiated and have no factual or legal basis. He did not address her specific charges, however, or directly deny charges she made that he has used secretarial services, and photocopy and mail facilities for right-to-life activities or personal financial business. Scanlon's executive assistant, John P. Mackey, said Scanlon would have no comment beyond his letter.

Public Citizen, a national public interest group founded by Ralph Nader, called on the Senate committee last month to request a federal investigation into the activities of Scanlon, who was nominated in a recess appointment by President Reagan in December and has not yet been confirmed by the Senate.

"Scanlon has used government staff and government equipment and facilities to perform work for the 'right-to-life' movement, and for personal business transactions, including real estate properties he owns and leases," Claybrook said in a Sept. 23 letter to the committee.

"This misuse of government staff and facilities for private purposes includes use of agency secretarial services, photocopy and mail facilities to prepare and distribute right-to-life materials, and to prepare bills and notices and deposit rents concerning his leases and personal finances; use of commission funds to pay for taxi fares, and other local travel costs to hand-carry right-to-life materials to various locations in Washington and to otherwise foster such activities," Claybrook said.

In response, Scanlon wrote in a letter dated Oct. 3 that he has "never permitted my religious views to compromise in any way the obligations, duties and responsibilities of the civil offices I have held."

"I have devoted over 20 years' service to the federal government, throughout which I have consistently taken care to separate my official duties from my personal matters, including the areas of photocopying, secretarial services, mail facilities and my personal finances," he wrote.

Claybrook also charged that Scanlon and the staff he brought to the agency are "known by numerous [CPSC] staff members to have violated [CPSC] rules governing meetings with companies and industries . . . on a number of occasions."

Among several specific charges, Claybrook alleges that Scanlon arranged for a private, closed-door meeting with representatives from the all-terrain-vehicle industry in Concord, N.H., on July 26. The CPSC currently is investigating ATVs, which are three-wheeled, off-road vehicles imported from Japan that have been growing in popularity in this country.

At least 233 people have died in accidents involving ATVs since 1982, according to the commission.

The New Hampshire meeting, held the day after an agency hearing on ATVs in Concord, was not listed on the agency's public calendar, and none of the commissioners were told about it, Claybrook said.

Instead, the requirement that all notices of meetings be submitted to the agency calendar seven days before they occur was waived, Claybrook said.

Scanlon states in his letter that Claybrook's allegation of a "secret meeting" in New Hampshire is "untrue." He goes on to write that the meeting did occur, a seven-day notice rule was waived, and the meeting was listed on the agency calendar on July 31, six days later.

Waivers of the seven-day notice requirement are "granted on a routine basis," he said.

However, a source who was involved in developing the agency calendar policy said, "It is not routine for members of the commission to waive the seven-day notice" for meetings with industry members on matters that were the subject of possible regulatory proceedings."