Following a pattern of blurring lines between advertising, public relations and lobbying, a Cincinnati-based advertising agency has opened "Corporate Communications Center" in Washington.

Among the services the Washington division of Fahlgren & Ferris offers according to its brochure, are those of former Federal Communications commissioner Richard E. Wiley and fromer Federal Trade commissioners Cal Collier and Mayo Thompson. However, a law partner of Wiley said that arrangements with Fahlgren & ferris have not het been completed and that it is not sure what shape the arrangement will take.

"We have organized a panel of experts unmatched by any other communications organization," the firm promises. "For example, if we need to secure TV clearance on a controversial matter, we turn to Dick Wiley . . ."

Among other big guns, the agency boasts the former president and chief executive officer of Benton & Bowles and former president of the American Association of Advertising Agencies William R. Hesse and Salvatore F. Divita, chairman of the department of business administration at George Washington University.

The firm will also have a relationship with the accounting firm Coopers & Lybrand.

"What is happening is that the fastest growing segment is corporate and advocacy advertising," said Hesse. That growth will be helped by a recent Supreme Court decision striking down government bans against advertising and political propagandizing by utilities saying it violated the companies' right to free speech.

Increasingly corporations have taken a public relations offensive, portraying themselves as the good guys on environmental and other public issues and rallying public support for their causes. "Business advocacy," as Fahlgren & Ferris called it, has become something of a minor boom in PR.