Belarusian President Alexander Lukashenko freed 123 prisoners on Saturday including Nobel Peace Prize winner Ales Bialiatski and leading opposition figure Maria Kalesnikava after two days of talks with an envoy for U.S. President Donald Trump.

In return, the U.S. agreed to lift sanctions on Belarusian potash. Potash is a key component in fertilisers, and the former Soviet state is a leading global producer.

The prisoner release was by far the biggest by Lukashenko since Trump's administration opened talks this year with the veteran authoritarian leader, a close ally of Russian President Vladimir Putin.

Western governments had previously shunned him because of his crushing of dissent and backing for Russia's war in Ukraine.

Nine of the released prisoners left Belarus for Lithuania and 114 were taken to Ukraine, officials said.

Bialiatski, co-winner of the 2022 Nobel Peace Prize, is a human rights campaigner who fought for years on behalf of political prisoners before becoming one himself. He had been in jail since July 2021.

Visibly aged since he was last seen in public, he smiled broadly as he embraced exiled opposition leader Sviatlana Tsikhanouskaya on arrival at the U.S. embassy in Lithuania.

Bialiatski told Reuters he had spent the previous night on a prison bunk in a room with nearly 40 people, and was still getting to grips with the idea of being free.

He said the goals of the human rights struggle for which he and his fellow campaigners had won the Nobel prize had still not been realised.

"Thousands of people have been and continue to be imprisoned ... So our struggle continues," he said in his first public comments in the three years since he won the award.

The Norwegian Nobel Committee expressed "profound relief and heartfelt joy" at his release.

Kalesnikava, a leader of mass protests against Lukashenko in 2020, was among the large group taken by bus to Ukraine.

"Of course, it's a feeling of incredible happiness first of all: to see with your eyes the people who are dear to you, to hug them, and understand that now we are all free people. It's a great joy to see my first free sunset," she said in a video published by the Ukrainian Telegram channel Khochu Zhit.

It showed her embracing Viktar Babaryka, an opposition politician arrested in 2020 while preparing to run against Lukashenko in an election. Babaryka said his son Eduard was still in prison in Belarus.

Tatsiana Khomich, Kalesnikava's sister, told Reuters she had been worried she might refuse to leave Belarus and had been prepared to try to persuade her.

"I very much look forward to hugging Maria... the last five years was very hard for us, but now I talked to her (by phone) and I feel as if the five years did not happen," she said.

U.S. officials have told Reuters that engaging with Lukashenko is part of an effort to peel him away from Putin's influence, at least to a degree - an effort that the Belarus opposition, until now, has viewed with extreme scepticism.

Trump's envoy, John Coale, had earlier told reporters in Minsk: "Per the instructions of President Trump, we, the United States, will be lifting sanctions on potash."

The U.S. and the European Union imposed wide-ranging sanctions on Belarus after Minsk launched a violent crackdown on protesters following a disputed election in 2020, jailing nearly all opponents of Lukashenko who did not flee abroad.

Sanctions were tightened after Lukashenko allowed Belarus to serve as a staging ground for Russia's invasion of Ukraine in 2022.

The exiled Belarusian opposition expressed gratitude to Trump and said the fact that Lukashenko had agreed to release prisoners in return for the concessions on potash was proof of the effectiveness of sanctions.

The opposition has consistently said it sees Trump's outreach to Lukashenko as a humanitarian effort, but that EU sanctions should stay in place.

"U.S. sanctions are about people. EU sanctions are about systemic change — stopping the war, enabling democratic transition, and ensuring accountability. These approaches do not contradict each other; they complement each other," exiled opposition leader Sviatlana Tsikhanouskaya said.

Lukashenko has previously denied there are political prisoners in Belarus and described the people in question as "bandits." As recently as August, he asked why he should free people he sees as opponents of the state who might "again wage war against us."

Trump has referred to Lukashenko as "the highly respected president of Belarus," a description that jars with the opposition, who see him as a dictator. He has urged him to free up to 1,300 or 1,400 prisoners whom Trump has described as "hostages."

"The United States stands ready for additional engagement with Belarus that advances U.S. interests and will continue to pursue diplomatic efforts to free remaining political prisoners in Belarus," the U.S. embassy in Lithuania said.

Belarusian human rights group Viasna — which is designated by Minsk as an extremist organization — put the number of political prisoners at 1,227 on the eve of Saturday's releases.