Two prominent female rights activists who went to the aid of a woman they believed to be in distress are expected to go to jail in Saudi Arabia on Sunday after the failure of their appeal against a 10-month prison sentence and a two-year travel ban.

Wajeha al-Huwaider, a writer who has repeatedly defied Saudi laws by driving a car, and Fawzia al-Oyouni were arrested for taking a food parcel to the house of someone they thought was in an abusive relationship. In June they were found guilty on a sharia law charge of takhbib – incitement of a wife to defy the authority of her husband, thus undermining the marriage.

Campaigners say they are "heroes" who have been given heavy sentences to punish them for speaking out against Saudi restrictions on women's rights, which include limited access to education and child marriage as well as not being able to drive or even travel in a car without a male relative being present.

In 2007 a Saudi appeal court doubled a sentence of 90 lashes to be given to a teenager because she had been in a car with a male friend when they were abducted and gang-raped by seven men.

Suad Abu-Dayyeh, an activist for the group Equality Now , said the authorities had been trying to silence the two women for years and their sentence "is unfortunate and scandalous". It marked a dangerous escalation of how far Saudi authorities were willing to go.

"These women are extremely brave and active in fighting for women's rights in Saudi Arabia, and this is a way for the Saudi authorities to silence them," she said. "If they are sent to jail, it sends a very clear message to defenders of human rights that they should be silent and stop their activities – not just in Saudi Arabia, but across Arab countries. These women are innocent – they should be praised for trying to help a woman in need, not imprisoned. They now find themselves at the mercy of the system they have fought so tirelessly to change."

According to reports, this is also the first time in Saudi legal history that a travel ban has been imposed in a case involving domestic issues.

"This case and the system of lifelong male guardianship of women in Saudi Arabia shows that protecting a husband's dominant, even abusive, position in the family is far more important than his wife's wellbeing," said Suad Abu-Dayyeh.

The women themselves believe they may have been set up, that they were contacted by text message by a woman claiming to be the mother of Natalie Morin, a Canadian national married to a Saudi who has herself been campaigning for several years to be allowed to leave the country with her three young children – something she says the authorities will not allow her to do.

The text, in June 2011, said she had been abused by her husband, an unemployed former Saudi intelligence officer, who had then left for a wedding and left her and her children locked in their apartment in the eastern city of Dammam for a week and that they were running out of food and water. When the two women arrived in Morin's street they were immediately arrested.

"Actually when we went to there, the minute we arrived a police car arrived," said Wajeha al-Huwaider. "I'm sure the judge knows that it was a trap and they meant to catch us at that time in order to make a case against us."

At first they were charged with trying to aid Morin escape to the Canadian embassy in Riyadh, but the intervention of a local member of the Saudi royal family led to those charges being dropped, because, said Huwaider, even he was embarrassed at the obvious nature of the set-up.

Morin was also arrested and held for several hours. It was not until a year later that the two women were told they were to face the new charge of takhbib, a law that effectively puts all aid workers and activists helping Saudi women in need of protection from domestic violence, at risk.

Morin was not permitted to testify at their trial earlier this year that she had never met Huwaider and Oyouni. She has declared support for them on her blog writing: "I am sorry for what's happening to madam Wajeha al-Huwaider and her friend." She said the "two Saudi women find themselves in a serious legal problem with jail just for trying to help me … there is no evidence for the charges that are against her and her friend."

Huwaider and Oyouni's conviction has been condemned by numerous human rights organisations, including the Gulf Centre for Human Rights, Human Rights Watch, Equality Now and Pen International.