The Russian figure skating star at the center of doping questions at the Beijing Olympics will be allowed to compete in the women’s singles event after a ruling by a panel of arbitrators on Monday.

The panel, in a statement, said it would be unfair and cause “irreparable harm” to the skater, Kamila Valieva of Russia, if she were barred from the competition, despite having tested positive for a banned substance in December. That revelation came last week, after Valieva had helped lead Russia to first place in the team event.

Valieva, 15, has become a face of the Games and is widely seen as the favorite to win the women’s event that begins on Tuesday.

At a practice session a half-hour after the ruling, she performed her usual array of jumps and spins impeccably as more than a hundred journalists looked on. She left the rink, carrying a favorite stuffed rabbit toy, without speaking to reporters.

While the ruling means Valieva can begin her pursuit of a second gold medal at these Games, questions will surely hang over her performance and the Russian team, as well as the system meant to ensure that athletes taking part in major global competitions are clean.

The panel ruled on a narrow question: Did Russia act improperly when it lifted a suspension of Valieva last week only one day after imposing it? That decision effectively cleared the path for Valieva to compete in the singles event, but three international organizations — the International Olympic Committee, the World Anti-Doping Agency and skating’s global governing body — immediately challenged it in appeals to the Court of Arbitration for Sport, the highest legal authority in global sports.

In its decision, the panel said it “considered fundamental principles of fairness, proportionality, irreparable harm and the balance of interests” between Valieva and the organizations seeking to bar her from the Games. Also, it noted, Valieva was a minor and did not test positive at the Beijing Games, though she could face penalties when her case is examined after the Olympics.

The panel was not charged with deciding whether Russia should keep the gold medal in the team competition, a prize earned with the help of Valieva’s stunning performances in the women’s portion. Nor did it consider the question of whether Valieva was guilty of knowingly using a banned drug. But it did question the timing of the events, saying there were “serious issues of untimely notification of the results.”

Matthieu Reeb, the director general of the court, announced the ruling at a news conference in Beijing on Monday, less than 30 hours before the women’s event was to begin. He lamented the delay in processing Valieva’s sample, which was collected Dec. 25 but not returned — with the positive result, until last Monday — after she had begun competing in the Games. Reed left the room after making the announcement without answering reporters’ questions.

The World Anti-Doping Agency expressed “disappointment” in the decision, and said in a statement that the panel had ignored specific provisions of the antidoping code that governs athletes, and which required a suspension — even for a teenager.

Within minutes of the ruling, the United States Olympic and Paralympic Committee issued a statement expressing its disappointment. Sarah Hirshland, the chief executive of the committee, said that clean athletes were being denied “the right to know they are competing on a level playing field.”

“We are disappointed by the messages this sends,” Hirshland said, adding, “This appears to be another chapter in the systemic and pervasive disregard for clean sport by Russia.”

Tricia Smith, the president of the Canadian Olympic Committee, said it was “extremely disappointed” with the result. Canada won fourth in the team event, behind the United States and Japan, but could be elevated to bronze if a later ruling on the substance of Valieva’s doping case leads to a change in the final order.

The team medals have not yet been awarded, and it is unclear if they will be presented at the Games. The final resolution of questions of Valieva’s eligibility could take months to sort out.

Groups upset by the ruling denounced previous decisions that have allowed Russian athletes to compete at these Games even as their country is banned from them after it was caught orchestrating a state-sponsored doping scheme at the 2014 Games in Sochi. As part of its punishment, Russia’s name, flag and anthem are prohibited at the Beijing Games; its athletes who have been cleared by their individual sports federations are competing under the banner of the Russian Olympic Committee.

“Russia has never been incentivized to reform because sport leaders favored politics over principle and rebranding over banning,” said Rob Koehler, the director general of Global Athlete, an athlete advocacy group.

Valieva tested positive for trimetazidine, a heart medication that could increase endurance. Her positive result came from a urine sample that was taken from her at the Russian national championships on Dec. 25 but not confirmed by the Stockholm lab entrusted with testing it for about six weeks.

The Russian antidoping agency said it had received notice from the Swedish lab of Valieva’s failed drug test only on Feb. 7, the same day that she led the Russians to a gold medal in the team event.

“This is a very complicated and controversial situation,” her coach, Eteri Tutberidze, told Russia’s state-run TV network Channel One on Saturday. “There are many questions and very few answers.”

Despite those unknowns, Tutberidze declared that “we are absolutely confident that Kamila is innocent and clean.”

In last week’s free skate in the team competition, Valieva became the first woman to land a quadruple jump. Her performance led the Russians to win the team event, their best showing ever.

In the weeks following the Olympics, though, Valieva’s case will continue, and could end up back at the Court of Arbitration for Sport in Switzerland for new rulings by new panels.

Because she is only 15 she is recognized as “a protected person” under antidoping rules, her case will be assessed under different standards of evidence, and she would face lesser penalties, if any, than adults would.

The people more likely to face punishment would be any of her coaches, trainers and medical personnel who might have known about her use of the drug, or who might have provided it to her. Both the Russian antidoping agency and WADA said they would investigate those people.

It is also possible Valieva could receive only a reprimand for using the banned drug, or for having it in her system.