WASHINGTON — The State Department said today that the five permanent members of the U.N. Security Council have approved a peace mission to Tehran by U.N. Secretary-General Javier Perez de Cuellar, and the Reagan Administration delayed a deadline for Iran to agree to a cease-fire in the Persian Gulf.
State Department spokesman Charles E. Redman said Perez de Cuellar will visit Tehran next Thursday.
Redman said the Perez de Cuellar visit had the approval of the five permanent members of the council--the United States, the Soviet Union, Britain, France and China. He said they had reached agreement on conditions for the peace mission after three days of informal discussions in New York.
The Administration had given Iran until Friday to obey the cease-fire ordered by the Security Council on July 20. But Redman said drafting of sanctions against Iran by the council would be delayed until after Perez de Cuellar's Tehran visit.
However, the U.S. official said: "We believe the time for stalling has come to an end. There is a need for a definitive response."
Redman said Iran issued its invitation to Perez de Cuellar after the State Department on Tuesday announced its intentions to move toward sanctions, which probably would entail an arms embargo, unless Tehran agreed by Friday to stop fighting and to negotiate with Iraq.
Representatives of all 15 Security Council members, including American and Soviet diplomats, were working at the United Nations in New York on instructions for the mission.
No Changes in Resolution
It was understood the United States had demanded as a condition for its approval that Perez de Cuellar not permit Iran to change the cease-fire resolution. Tehran's chief objection is that the measure did not cite Iraq as the aggressor in the gulf war.
The decision to approve the mission reflected U.S.-Soviet cooperation, but it was unclear whether Moscow would support sanctions if Perez de Cuellar failed to elicit a positive response from Iranian leaders.
As a permanent member of the Security Council, the Soviet Union has the power to block the resolution with a veto.
Redman said he did not know whether Iran's invitation to Perez de Cuellar was a tactical delay or a genuine move to consider accepting the cease-fire. "It's not possible for me to make that kind of evaluation," he said.
Goal Is End to War
"We've said from the start that our goal in all of this is to achieve implementation of this resolution which would finally bring this war to an end," Redman said. "If that's what this visit can help to do, then we'll give that a chance."
But he also stressed that the United States wanted a "definitive response" from Iran to the resolution, which calls also for negotiations to settle the gulf conflict with Iraq.
The two countries have been at war in the Persian Gulf area for seven years. Iraq agreed to the cease-fire, but Iran has not given a concrete reply.