A third round of indirect talks between Afghanistan and Pakistan regarding the war in Afghanistan will take place in Geneva in August. Two similar rounds of Geneva talks in 1982 and 1983 produced some procedural progress but no substantive achievements.
United Nations Secretary-General Javier Perez de Cuellar now has decided to ''go the extra mile'' in attempting to work out a negotiated settlement to the war because ''Afghanistan and Pakistan have, at least marginally, shown some flexibility in recent days,'' according to a reliable diplomatic source here at the UN. In the past Pakistan has refused to even acknowledge the Afghan regime.
Western diplomats remain cautious, however. United States diplomats in particular don't conceal their skepticism about the usefulness of the coming talks. ''There is nothing to indicate that the Soviets are in a conciliatory mood toward Afghanistan,'' says one American official.
Other well-informed diplomats point to recent agreement on certain procedural concessions by Pakistan and Afghanistan.
Two months ago, UN undersecretary for political affairs, Diego Cordovez, went to Kabul, Islamabad, and Tehran. He came back empty-handed, but hoped Pakistan and Afghanistan would send him answers to several points he had raised and on which the UN go-ahead for a third round of talks depended.
These answers now have been delivered, and allow, in his view, for some movement. Specifically:
* Pakistan now will allow ''indirect'' proximity talks. This means the Geneva talks will take place in one building but the parties will not meet face to face. Diego Cordovez will have to shuttle between rooms.
* Afghanistan, which up to now insisted on concluding separate bilateral agreements with Pakistan, the Soviet Union, and with a group of major powers, now is willing to discuss the four points set forward by the UN Secretary-General which, as a package, could form the basis for a peaceful settlement.
These include: 1) the phased-out withdrawal of Soviet troops; 2) the gradual return of Afghan refugees; 3) international guarantees on noninterference in internal Afghan affairs by its neighbors and by the five permanent members of the Security Council; and 4) free choice by the Afghan people for their own form of government.
Some observers, however, say these procedural concessions hardly justify a new round of talks.
''The Afghan refugees (who presumably speak for the Afghan rebels) will still not be represented at the Geneva talks, and there is not the slightest indication that the Soviets will present a calendar for (Soviet) withdrawal from Afghanistan as part of a package,'' says one informed Western diplomat.
On the other hand, Mr. Perez de Cuellar is expected to visit Moscow in July and meet with Soviet leader Konstantin Chernenko and Foreign Minister Andrei Gromyko. The Secretary-General ''hopes that, having shown his good will in authorizing the talks, that the Soviet leaders will show their good will and make some concessions during his stay in Moscow,'' says one aide to Perez de Cuellar.