U.S. and Russian officials are poised to announce swift resumption of manned missions to the International Space Station, after determining that last month's failure of an unmanned cargo rocket headed to the orbiting laboratory was likely an isolated incident.

Transporting crews to the station on Russian-built Soyuz rockets could resume as early as mid-October, according to U.S. government and industry officials. Such a schedule, which could be announced shortly, would seem to ensure that the $100-billion station won't have be left temporarily unmanned as a result of last month's failed Soyuz rocket launch.

The status of the Soyuz rockets is of critical importance to efforts to keep personnel from the U.S. and other nations aboard the space station. With the July retirement of the U.S. space shuttle fleet, for now Russia's workhorse Soyuz boosters are the only way to regularly ship materials or people into orbit. Manned spaceflights use the same models of Soyuz rockets as last month's failed cargo launch.

The August mishap, in which a rocket fell back to Earth without reaching orbit, resulted from a Soyuz third-stage motor that malfunctioned because of what officials now believe was an isolated manufacturing defect. The episode disrupted long-standing schedules to replace astronauts manning the space station.

It also prompted government experts from both countries to announce that they wanted to demonstrate reliability of the boosters by first requiring two successful unmanned cargo missions to dock with the station, orbiting 200 miles above the earth.

Under some circumstances, that plan could have stretched past early November, when the last of the crew members currently at the station are slated to depart and return to earth. The result, NASA officials previously warned, could have meant leaving the station without any crew until manned Soyuz flights started again.

But now, according to U.S. industry and government officials, experts in Washington and Moscow anticipate that manned flights will pick up more quickly, so they are backing away from those earlier contingency plans.

On Friday, Russian space officials announced that a clogged fuel-supply line on the upper stage was the culprit behind the botched August launch. Indicating the problem was a production quality-control lapse rather than a design flaw, investigators said other batches of rocket motors would be checked.

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U.S. officials were buoyed by the latest findings, particularly because resolving similar Russian production-related mistakes in the past created only relatively minor delays in launch schedules. Roskosmos, the Russian space agency, didn't announce a revised schedule for Soyuz missions.

Soyuz rockets, which launch more frequently than their Western counterparts, have an excellent reliability record stretching back many years. Until the August accident, the same rocket configuration had racked up approximately 100 successful launches in a row, according to industry officials.

The U.S. National Aeronautics and Space Administration has scheduled a news briefing on Monday to discuss the matter. A NASA spokesman declined to comment.

Even before the Russian announcement, however, high-level NASA officials were backing away from requiring a pair of cargo launches to verify safety of the system. Last week, NASA chief Charles Bolden sent an email to agency employees indicating that plans called for "at least one unmanned booster" to fly before Soyuz could be cleared to launch crew

In response to questions, on Wednesday the agency issued a statement stressing that "it is premature to speculate on how many flights may be required."

During a visit to NASA's Florida launch complex the same day, Mr. Bolden was quoted by the Florida Today newspaper saying that a single cargo flight would be adequate "to demonstrate that Soyuz is still OK, and then we'll fly the crew up on a normal Soyuz mission later this fall."

In the same article, Mr. Bolden was quoted saying that the possibility of having to temporarily pull all astronauts off the space station wasn't a major concern: "We don't feel that is something we're going to have to do."

In addition to the conclusions of Russian investigators about the August failure, people familiar with the matter said NASA officials also seem increasingly sure that astronauts would be able to survive and safely return to earth in their capsule in the event of another third-stage propulsion failure. In light of such safeguards, NASA managers have decided additional cargo flights aren't essential.