President Lyndon B. Johnson informed the nation last night that he has ordered a total halt of bombing of North Vietnam.

The television announcement came after an hour-and-a-half White House meeting with top diplomatic and military advisers, and confirmed recent speculation that such a decision was in the offing. The bombing halt takes effect at 8 a.m. EST today.

Johnson stated that the cessation was not only of bombing, but of all acts involving the use of force, including troop activity, in the North. Unarmed reconnaissance is still permitted, however, he said.

Not Final

The President added that the bombing halt was not final. If the North Vietnamese should abuse the Demilitarized Zone, attack cities or provincial capitals, or refuse to enter into serious discussion about ending the war, the United States could resume bombing. Hanoi must also agree to let the elected government of South Vietnam join in the negotiations.

Johnson asserted that, "What we now expect--what we have a right to expect--are prompt, productive, serious, and intensive negotiations in an atmosphere that is conducive to progress." He added that Hanoi has already indicated an intention to talk more seriously. The discussions will resume Nov. 6 with the N.L.F. also participating.

Many observers predicted that last night's announcement would help Vice President Humphrey in his uphill fight against front-running Richard Nixon in next Tuesday's Presidential election.