`When the bombs went off at Zaventem airport last week, Jasmine was seized first by fear for her own life and others due to fly with her. But another dread was lurking, too: that her sons who left Brussels for Syria in 2013 could have been involved.

“You never know,” she said. “I have had that fear since the November events [in Paris] but I decided to stop thinking that way because it is a negative attitude that serves no purpose in making things better.”

Jasmine, who was at the airport at the time of last week’s bombing, is furious that her boys were allowed to leave at all. She had warned police of fears that her older child, Moussa, had been radicalised and might be planning to leave for Syria after finding a passport and a ticket to Istanbul by his bed on Christmas Eve 2012. The police were not interested. “They just said: ‘No, your son is 22. He is an adult. We have no file on him and it’s not forbidden to travel to Syria and fight against Bashar, so we can’t do anything for you’.”

Her younger son, Rashid, followed three months later, when he was still only 16. He told his mother he was going to the movies and on for a bowling game with some friends, and that evening he called home from Istanbul.

“How come he could cross the border at Zaventem when he was under 18? The airport authorities should have stopped both of them,” she told the Observer. “I was totally shattered. I only had the energy to call the police and ask them to go and bring him back.”

She has been campaigning against radical groups, and for the rehabilitation of their recruits, since 2013, but her anger is not directed only at extremists. The government has betrayed her children, too, she says, happy to let radicals leave, even tacitly encouraging them.

“Today they all say, ‘we never would have imagined, we never knew’, but actually they were accomplices,” she said. “Our children are first victims of a criminal organisation that brainwashed them. But they are also victims of our political leaders and foreign minister.”

A few days after Rashid left Brussels, Didier Reynders, Belgium’s foreign minister, said of those going to fight: “One day, perhaps, we will build a monument for them as heroes of the revolution.”

Moussa had been an ambitious mechanical engineering student and he dreamed of developing engines for racing cars. But after a chance encounter in Molenbeek with a radical preacher – who is now on trial for recruiting young men to Isis – he started to become withdrawn.

The only warning he gave Jasmine on the day of his departure was an unusually long goodbye hug in the kitchen. As he walked out to his car, “he said ‘forgive me, mama, for all the hard times I gave you over Christmas’,” Jasmine explained. “I didn’t realise he was actually kissing me goodbye.”

Rashid was quieter than usual, apparently devastated after his brother left, but a family therapist told them that this was normal behaviour for someone who had just lost his brother to a war zone. “We blamed it on the fact that he was in shock,” Jasmine said. “We never imagined that something different was brewing.”

Since then, her only contact with her children has come by way of clipped text messages. “They occasionally send us a message to ask about the family and tell us that they have faith. They always say they are in safe areas and we shouldn’t worry but, apart from that, we have no clue.”

Jasmine, Moussa and Rashid are all pseudonyms