A coalition of 46 health, education, labor and public activist groups announced a one-week nationwide campaign yesterday designed to elicit public participation in the controversial Federal Trade Commission inquiry into television advertising aimed at children.

The coalition, headed by Action for Children's Television, urged citizens to spend an hour watching children's programming during the next seven days and write the FTC about their opinions of the advertising they see.

"Never before . . . has there been a better opportunity to help change a system that permits children to be manipulated for private gain." ACT President Peggy Charren said at a press conference yesterday. The letters will make a difference."

Nov. 24 is the closing date for comment from the public.

The FTC began the formal proceeding in the spring to look into problems posed by television advertising aimed at children and to decide whether the agency should take any action.

The FTC staff had recommended to the five-member agency that it propose a ban of TV commercials aimed at children "too young to understand the selling purpose" of advertising, a ban on the advertising of highly sugared products to children under the age of 12 and a requirement that advertisers of other sugared products aimed at youngsters contribute to a fund that would balance the ads with separate dental and nutritional messages.

The Proposals sparked a concerted lobbying effort on Capitol Hill oy representatives of sugar and food companies and the broadcasting industry to try to head off the FTC, as well as several legal challenges designed to thwart the effort.

Although attempts to get Congress to limit FTC spending on the project failed during the last Congress one legal challenge affecting the proceeding was successful. Early this month, U.S. District Court Judge Gerhard A. Gesell ruled that FTC Chairman Michael Pertschcuk could not participate in the proceeding because of his "emotional use of derogatory terms and characterizations" about children's advertising.

The three remaining members of the commission who are participating in the case will be deciding whether to appeal Judge Gesell's decision.

Newest member Robert Pitofsky is not participating because, when a professor at Georgetown Law School, he had served as chairman of the board of directors of a public activist law group that represented one of the two parties that petitioned the FTC to iniate the proceeding.)

Among the groups backing the watch-and-write campaign and whose representatives attended yesterday's press conference are the American Academy of Pediatrics, American Dental Association, American Public Health Association, Consumer Union, International Association of Machinists, NAACP, National Urban League, United Auto Workers and United Steel Workers.

Tipper Gore, the wife of Rep. Albert Gore Jr. (D-Tenn.), said the Congressional Wives Task Force, which she was representing, fully supported the FTC inquiry and hopes it can help heighten public awareness about children's advertising issues.

Dr. Philip L. Calcagno of the 15,000-member American Academy of Pediatrics said the academy believes "television advertising to children is unherently unfair since children lack the capacity to understand and evaluate the meaning or intent of television commercials."

Ideally, broadcasters and advertisers would display responsibility and restraint and refuse to exploit children, but "unfortunately this doesn't seem to be happening." Dr. Calcagno said. Although banning children's TV ads would be the most effective remedy, he said he knew political and economic realities may not permit that.

"Whatever happens, we believe that the issue must be addressed in a responsible way," he said. He added that parents also have the ultimate responsibility of monitoring television's influence on children.

Rev. Loring Chase of the United Church of Christ said the FTC proceeding was a "heaven-sent opportunity" to influence what children eat and see.

Ken Kovack of the United States Workers said the American people believe that government should act where the private sector has failed or has performed in an unsatisfactory way. Children's TV advertising falls into that category, he said.