NEW YORK (AP) _ A flickering TV screen soon may be competing for attention with the trashy tabloids and candy bars in the supermarket checkout line.

Cable television giant Turner Broadcasting System Inc. and ActMedia, a marketing firm specializing in promotions in the store, said Thursday they plan to design a new TV program service aimed at shoppers in the checkout line.

The so-called Checkout Channel will feature news, sports and other specially-tailored programming - plus advertising - on TV monitors placed above each checkout aisle.

Turner and ActMedia said they hope to have it installed in 5,000 of the nation's 30,000 supermarkets within two years.

Wayne W. LoCurto, chief executive and president of ActMedia, said the service should help advertisers reach a huge audience each week while making the wait in the checkout line more enjoyable for shoppers.

If the plan works, it would be the latest commercial encroachment into places that formerly were beyond the reach of television advertisers.

In recent months, media companies either have introduced or announced plans to develop commercial TV programs designed to reach teens in the classroom, women at the beauty salon and patients in the doctor's waiting room.

''There will be a few people to complain, but we believe the overwhelming majority of people will like it,'' LoCurto said in a telephone interview.

''It's informative, entertaining and it's going to make their wait seem to go quicker,'' he said.

Atlanta-based Turner Broadcasting has agreed to create specially-tailored programs of news, sports, business, weather and consumer information taken mainly from its Headline News cable network. Each eight-minute program will include 2 1/2 minutes of commercials.

The programs will be delivered by satellite 24 hours a day to participating stores which will be equipped with TV monitors above each checkout aisle.

ActMedia plans to provide the 50,000 TV sets and the satellite hardware.

LoCurto said that as a convenience to shoppers who don't want to be constantly bombarded with the show, the sets will be designed so that the sound shuts off unless someone approaches within a half-dozen feet of the monitor.

But once someone gets in line, there will be no way to shut the set off or adjust the volume, he said.

He said the programs are being designed as eight-minute shows, roughly the same amount of time as the average wait in a checkout line.

Turner and ActMedia plan to test the system from August through October in 12 stores in six cities, although they would not name the cities. LoCurto said plans are to begin a national service in the first quarter of 1991 and said he hopes to have the Checkout Channel in 5,000 stores by mid-1992.

LoCurto declined to give the cost of launching the system or the relative investments of Turner and ActMedia are in the venture.

ActMedia expects to generate about $100 million a year in revenue from the the two minutes of advertising time it sells on each eight-minute program, while Turner will get to keep proceeds from the ads in the remaining half- minute.

LoCurto said Actmedia will share some of its revenue with the stores that agree to install the system. Advertisers will be asked to pay rates roughly equivalent to those charged on daytime television.

Ad time will be sold for terms of a year or more with an annual rate of about $12 million for a 15-second ad in each show when the system is in full operation and reaching 30 million to 40 million people a week in 5,000 stores.

ActMedia, based in Darien, Conn., and a unit of Heritage Media Corp. of Dallas, Texas, was founded in 1973 and is the leader in in-store marketing programs. It operates couponing and sampling programs and places advertising on shopping carts, aisle directories and store shelves in 20,000 supermarkets.