Opposition leader Maria Kolesnikova, one of the trio of women who campaigned against Belarus' self-appointed President Alexander Lukashenko in the August 9 presidential election, is still missing 12 hours after masked men bundled her into a van in central Minsk. Her campaign team has listed her as a “missing person”, after the authorities denied arresting her and claimed to have no knowledge of her whereabouts.

“Ominous: according to her campaign’s twitter account, Belarusian opposition leader Maria Kolesnikova has been declared a missing person, and the police have mounted a search after she was abducted in Minsk today,” tweeted Felix Light, a high-profile Belarus observer.

Kolesnikova was bundled into a van marked “Connections” (a word associated with telecoms in Russian) near the National Art Theatre in central Minsk at about 10am on the morning of September 7 by a group of masked men. The van then drove away to an undisclosed destination.

The last of the three opposition leaders still in Belarus, her disappearance has been dubbed a “kidnapping” and her colleagues fear for her safety. Previously in 2010 several high-profile opposition leaders also disappeared and were never seen again. It is widely assumed they were murdered by Lukashenko’s regime and the EU subsequently slapped sanctions on the country as a result.

The German foreign ministry issued a strongly worded statement demanding the authorities find Kolesnikova and release her.

“We are greatly concerned about the fate of Maria Kolesnikova. Observing massive repression of the peaceful opposition the EU is urgently finalising a sanctions package. If Mr Lukashenko does not change course, we will take action,” the German foreign ministry said in a tweet.

On the same day that Kolesnikova was taken two more of her team disappeared.

“Maryia Kalesnikava, Anton Radniankou, Ivan Kravcov were kidnapped, snatched from street this morning. It's the end of the day in #Belarus, and there has been no information where they are. I want to see more international alerts with this news and calls for their release,” tweeted Hanna Luibakova, a local journalist.

The Ministry of the Interior denied Kolesnikova had been arrested in comments to the Russian news agency RIA Novosti.

Journalists at Tut.by called Kolesnikova's phone, which was working, but no one picked up.

Kolesnikova is the only one of the trio, also consisting of of Svetlana Tikhanovskaya and Veronika Tsepkalo, who is still in Belarus. She has been a prominent face at the weekly mass rallies and a leading figure at the women-only rallies that have been held on the last two Saturdays.

Kolesnikova is also a member of the newly established Coordinating Council that is calling for talks with the state on forming a transition government and holding fresh elections. Lukashenko has refused to recognise the Coordinating Council and the prosecutor's office has opened dozens of cases against the committee, accusing it of attempting to organise a coup d'état.

Only two members of the Coordinating Council’s leadership committee are still at liberty.

Kolesnikova's colleagues are afraid that Kolesnikova may be charged, as the state has opened dozens of criminal cases against the Coordinating Council, accusing it of trying to organise a coup d'état. Or that she will be driven into exile.

Previously Tikhanovskaya was forced into making a statement calling on the people to respect the falsified election results and end the demonstrations, before she was forced into exile in Lithuania, where she continues to campaign against Lukashenko.

Lukashenko has been slowly ramping up pressure on the protest movement. Another mass rally was held on September 6 with somewhere between 100,000 and 250,000 people in attendance. However, at this latest rally, that met under the slogan “unity”, the police presence was higher than at the previous rally and unmarked vans have been patrolling Minsk, randomly snatching pedestrians from the street.

NGOs reported that 633 people were detained over the weekend in the latest sign that Lukashenko is attempting to slowly turn the screw on the protest movement.