NEW YORK (AP) _ Two of the Public Broadcasting Service's top programmers, including its first chief programming executive, have resigned.

Chief programmer Jennifer Lawson and her senior vice president, John Grant, said they will leave the service on March 10. PBS President Ervin S. Duggan announced their resignations Friday in a news release from PBS headquarters in Alexandria, Va.

Both Lawson and Grant blamed their departure on Duggan's decision earlier this month to split PBS into three operating divisions.

``I've been here now for five years and it's been five wonderful years,'' Lawson said in a telephone interview. ``I wouldn't even consider this, had not my role ... within the company changed.''

Lawson became PBS' first chief programmer in 1989. During her tenure, PBS aired its two most-watched series, ``The Civil War'' and ``Baseball'' by Ken Burns. She also is credited with launching PBS' Children's Initiative, which nearly doubled PBS' preschool viewership.

Grant oversaw PBS' coverage of the Gulf War in 1990 and negotiated PBS' partnerships with NBC for 1992 election coverage and with Disney on the popular ``Bill Nye the Science Guy.''

Duggan's reorganization divided PBS operations into Programming Services, Learning Ventures and System Services, and created a new syndicated programming subdivision outside Lawson's authority.

Bob Ottenhof, PBS' executive vice president and chief operating officer, was named acting head of Programming Services, with Lawson reporting to him.

Neither Lawson nor Grant said they had any immediate career plans.

``Wherever I am, I'll still be a fan of public television,'' Lawson said.