MOSCOW — A Belarusian opposition leader who played a key role in leading recent anti-government demonstrations was arrested after she tore up her passport to avoid being expelled to neighboring Ukraine early Tuesday, local media outlets reported.

The decision to arrest Maria Kolesnikova was the right one, said longtime authoritarian Belarusian President Alexander Lukashenko, who is facing unprecedented protests after a widely condemned presidential election. He said she was being held for violating a border-crossing rule.

In a TV interview with Russian state media, Lukashenko, who has held the reins of power for 26 years, also acknowledged that “probably I have stayed on a little too long.” But he added that “only I can protect Belarus now,” rejecting protesters’ demands that he step down.

“No way I’m going to resign just like that,” he said. “I’ve been developing Belarus for a quarter of a century. I’m not going to give it all up.”

Lukashenko also ruled out meeting with the Coordination Council, which was set up by the opposition in hopes of negotiating a power transition.

Kolesnikova was seized early Monday by a group of masked men — apparently state security agents — and shoved into a van, a witness told local media. Ivan Kravtsov, a member of the Coordination Council, and Anton Rodnenkov, its spokesman, vanished around the same time.

Early Tuesday, they were taken to the border with Ukraine, according to local media reports. It is not clear who was driving, but in recent instances when opposition figures were expelled from the country, they recounted being driven by state security agents.

Since the Aug. 9 election, Belarusian authorities have been arresting opposition activists and members of the Coordination Council and expelling them from the country. Others have fled after warnings that they faced prison time.

“It was not a voluntary trip,” Ukrainian Deputy Interior Minister Anton Gerashchenko posted on Facebook, referring to the actions against Kolesnikova and the other two opposition figures. “It was a forced departure from their native country in order to compromise the Belarusian opposition, to make it look like the opposition leaders threw hundreds of thousands of protesters against Lukashenko’s regime and fled to cozy Ukraine.”

“Maria Kolesnikova could not be taken out of the country because this brave woman took measures to prevent herself from crossing the border,” Gerashchenko added.

Pavel Latushko, a member of the Coordination Council and a former culture minister and diplomat, said Kolesnikova tore up her passport at the border to avoid being expelled, Russia’s Interfax news agency reported.

The Coordination Council said Tuesday that Kravtsov and Rodnenkov had arrived in Kyiv, the Ukrainian capital, and that Kolesnikova was being detained by Belarusian border guards.

Kravtsov said at a news conference in Kyiv that they were transported to an area near Belarus’s border with Ukraine by the people who detained them. He said Kolesnilova tore up her passport in the buffer zone between the two borders and walked back to Belarus.

The official election results gave Lukashenko 80.1 percent of the vote, compared with just 10.2 percent for opposition candidate Svetlana Tikhanovskaya. The outcome has been rejected by the United States and the European Union.

Kolesnikova was one of three women who became the faces of the Belarusian opposition campaign after their husbands or associates were jailed or barred from running in the presidential election.

She is the last of the three to remain in Belarus. With other opposition leaders jailed or out of the country, Kolesnikova had emerged as an important rallying figure for the opposition.

Tikhanovskaya was escorted to the Lithuanian border last month after she tried to contest the validity of the election.

The third face of the opposition, Veronika Tsepkalo, fled Belarus for Poland a few days following the vote after purportedly receiving threats that she would be arrested. Her husband, former ambassador to the United States and businessman Valery Tsepkalo, had fled before the election, taking the couple’s two children.

Since the election, Lukashenko’s security forces have arrested thousands of people, including more than 630 at a peaceful protest Sunday attended by more than 100,000 people. Dozens of journalists and bloggers also have been arrested, while correspondents working for foreign news agencies have been stripped of accreditation by authorities.