Journalist and regime critic Roman Protasevich was due to fly from Greece to Lithuania on May 23 this year.
But instead of landing in Vilnius, the plane was forced down into Minsk - on the orders of Belarus' President Alexander Lukashenko.
At the airport, the 26-year-old activist and his girlfriend were arrested and taken away by police.
Belarusian authorities have released videos of Protasevich from prison, saying he is in good health.
Opposition leader Svetlana Tichanovskaya, however, is convinced that the activist is being tortured.
The mother: "Traces of violence in the face"
Now the telegram channel Nexta, which Protasevich co-founded, has published a clip with his parents.
In the video, they address themselves directly to their son:
- Please, keep strong.
So many people are working to get you released.
Hold on, we will help you and we will save you, says his mother Natalia Protasevich.
After taking part in the pictures that were spread about her son, she also shares Tichanovkaja's view of abuse.
- I know what he looks like and it was very clear that there were traces of violence in the face that had been made up.
The parents say that they do not know where Roman Protasevich is and that he is not allowed to receive visits from lawyers or independent doctors.
"Please help us"
Sweden and other EU member states have banned Belarusian aircraft in their airspace and the leaders are demanding that Roman Protasevich be released immediately.
However, his parents are demanding stronger efforts from the outside world to influence President Lukashenko.
- You must understand that every day, every hour, every minute delay can cost my son, and other young people who are behind bars, their lives.