MINSK, Belarus — The main opponent of Aleksandr G. Lukashenko, the embattled president of Belarus, left the country early Tuesday as organizers of the biggest antigovernment protests in its post-Soviet history called for a general strike.
Svetlana G. Tikhanovskaya, who ran for president in the election on Sunday after the jailing of her husband, an opposition blogger, was pressured to depart by the Belarusian authorities, two of her associates said. Linas Linkevicius, the foreign minister of neighboring Lithuania, said in a post on Twitter that Ms. Tikhanovskaya was in his country and was “safe.”
In a video released Tuesday that she appeared to have recorded under duress, Ms. Tikhanovskaya read from a prepared text calling on Belarusians not to resist the police or to protest in public squares in order “not to put your lives at risk.”
“I made this decision absolutely independently,” Ms. Tikhanovskaya said in another cryptic video message she released on Tuesday. “I know that many will understand me, many will judge me and many will hate me for it. But know that God forbid you will face the kind of choice that I faced.”
But many Belarusians who have been protesting against Mr. Lukashenko, the authoritarian who has ruled the Eastern European country for 26 years, appeared unlikely to heed her call for calm. The protests erupted after polls closed the country’s presidential election, in which Mr. Lukashenko claimed victory in a landslide. Critics believed the vote was blatantly rigged.
On Tuesday, social media accounts backing the protests urged a general strike. Anecdotes of factories halting production circulated on the Telegram messaging platform — the protesters’ primary means of communication — but they could not be immediately confirmed.
Earlier, protesters and the police clashed across the country for a second night. Protesters barricaded streets and riot police officers beat back crowds with baton charges, stun grenades, tear gas and rubber bullets.
The Belarus authorities said on Tuesday that 2,000 people had been detained across the country overnight, and that 21 law-enforcement and military personnel had been injured. In Brest, on the border with Poland, demonstrators were reported to have blocked roads with concrete benches and thrown broken paving stones at riot police officers, who responded by firing stun grenades.
Ms. Tikhanovskaya, a former English teacher, emerged as the face of the campaign against Mr. Lukashenko in recent weeks, with the established opposition figures, including her husband, in jail or in exile. The Belarus authorities allowed her name on the presidential election ballot, and the campaigns of two other challengers to Mr. Lukashenko — Viktor D. Babariko, a jailed ex-banker, and Valery V. Tsepkalo, who fled the country — endorsed her.
She traveled the country holding campaign rallies, exhorting Belarusians tired of years of economic stagnation and political repression under Mr. Lukashenko to call for change. The official results gave her just 10 percent of the vote in Sunday’s election, compared with 80 percent for Mr. Lukashenko, but the results were denounced as fraudulent by both the opposition and international governments.
On Monday, Ms. Tikhanovskaya visited the Central Election Commission headquarters in Minsk to officially contest the vote count. She was left in a room for three hours with two senior security service officials, according to Maria Kolesnikova, a supporter of Ms. Tikhanovskaya who said she accompanied her and waited outside the room during that meeting.
About an hour into the meeting, Ms. Kolesnikova said she saw several people with black bags containing what looked like video equipment enter the room. After another two hours, Ms. Kolesnikova was told that Ms. Tikhanovskaya had departed through another entrance.
She said she has not heard from Ms. Tikhanovskaya since, but added that it was clear that the candidate had recorded her video and left the country under pressure, with her husband, her friends and her supporters in custody.
“When all those around you and your family are hostages, it is very difficult not to make statements under pressure,” Ms. Kolesnikova told reporters in Minsk on Tuesday.
Mr. Linkevicius, the Lithuanian foreign minister, said in a news conference that Ms. Tikhanovskaya was in his country, where she had been together with her children.
“We found out that she experienced certain pressure and did not have much choice except to leave the country,” Mr. Linkevicius said.
In her video messages released Tuesday, Ms. Tikhanovskaya did not provide details about why she decided to leave Belarus or what sort of choice she faced. But she hinted that she had departed for the sake of her children.
“Not a single life is worth what is happening now,” she said. “Children are the most important thing we have in life.”
Ivan Nechepurenko reported from Minsk, Belarus, and Anton Troianovski from Moscow. Steven Erlanger contributed reporting from Brussels.