'It is their duty,' says Lina al-Hathloul, who has lived in exile for 10 years in Belgium and says she has never felt less safe than now.
'Absolutely I would encourage Newcastle fans to research the regime and realise that MBS [Saudi ruler, Mohammed bin Salman] controls their club.
'Otherwise they are legitimising a regime that has been absolutely toxic, and has been forbidden from much international engagement for years after the murder of Jamal Khashoggi.'
Al-Hathloul says that Newcastle's hierarchy - not least British businesswoman Amanda Staveley - have lied to fans about who really controls the club.
She says it is obvious that control ultimately lies with MBS, accused of atrocities including using a group of assassins known as the Tiger Squad to carry out extrajudicial killings of critics and enemies.
'But they [Newcastle] have been lying regarding the PIF and MBS's involvement in managing the PIF. They have lied and said the Saudi kingdom is not linked to the PIF and MBS has nothing to do with it.
'Maybe that's why fans now are turning a blind eye, and accepting the takeover, because that's the best solution for them, believing [lies]. If it was clear that MBS has taken over the club [himself], I don't think the fans would be so happy about it.
'Now it's like everyone is trying to forget about it and normalising relations again. Newcastle was the big first step for MBS to come back into the international sphere and it's dangerous.
'So of course I encourage the Newcastle fans to protest and point out the crimes that he is committing.'
Al-Hathloul's sister, Loujain, has been a women's rights activist since 2014 and was imprisoned for driving a car before it was made legal in Saudi Arabia in 2018. While in prison, Lina says: 'Loujain was beaten, electrocuted, waterboarded and force-fed. She was sexually harassed, and threatened with murder and rape. Because she is an activist.'
Loujain was released from prison earlier this year but is bound by strict rules that prevent her travelling outside Saudi Arabia and forbid her from any activism or talking about her situation.
'I used to feel safe but now it feels like the Saudi regime's efforts to silence dissidents and critics has never been so intense,' Lina says. 'I've never felt so threatened as much as now. Not just on Twitter, but family and friends have also been targeted … my family also have a travel ban.'