"Raise your heads up high – you're Egyptians!" hundreds of demonstrators chanted outside Saudi Arabia's Cairo embassy on Tuesday to protest the arrest and detention of Egyptian lawyer Ahmed El-Gizawi by Saudi authorities on Sunday.

The case of El-Gizawi, who was later sentenced by a Saudi court to one year in prison and 20 lashes for "defaming the king," has prompted a backlash in Egypt over the treatment of Egyptian nationals in the oil-rich kingdom and in other countries.

"El-Gizawi was arrested because he fought the discriminatory attitudes against Egyptians in Saudi Arabia and in other Arab and European countries," said 20-year-old protester Aya. "The law doesn't protect the rights of someone like El-Gizawi, while the American citizens recently accused in Egypt were repatriated on private planes."

She added: "Egyptians' dignity is always tarnished abroad."

El-Gizawi was sentenced after he filed a lawsuit in a South Cairo court against Saudi monarch King Abdullah Bin Abdel Aziz Al-Saud on behalf of Egyptians currently languishing in the kingdom's prisons without charge.

At Tuesday's protest in front of the embassy, a number of demonstrators carried banners bearing the image of relatives detained in Saudi, along with the number of years they had spent in prison. "Imprisoned without charge," several such banners read.

Mamdouh Zaky carried a banner depicting his detained son, Abdallah Mamdouh Demerdash, held in Saudi's Damam Prison since 2008. "My son has been in solitary confinement for three years now," the distraught father explained.

Demerdash's wife, Israa, who also took part in the protest, said her jailed husband had remained so isolated from the outside world that he had been unaware of last year's revolution in Egypt.

"The guards don't allow him to read newspapers," she said. "When I tried telling my husband that Mubarak and his sons were in prison, the guard threatened to cut the line if I continued to talk about the revolution."  

 According to Zaky, Demerdash faces no criminal charges.

"My son was arrested simply for expressing sympathy for the people of Palestine and Iraq," he explained. "Most prisoners currently languishing in Saudi prisons were arrested for speaking against the US or voicing their opinions online."

"King Abdullah, you're a coward and an agent of the US!" demonstrators chanted. "We want a revolution for freedom and against reactionary regimes!"

Protesters also expressed anger against the Egyptian government, which, they asserted, had failed to protect its citizens. "The problem isn't with Saudi Arabia, but with the authority of the Egyptian state," they shouted.

Some activists spray-painted slogans condemning the Saudi monarch for exploiting the Islamic hagg and umrah pilgrimages to arrest non-Saudi Muslim dissidents, as had been the case with El-Gizawi.   

Egyptian Foreign Ministry spokesman Amr Rushdy said earlier on Tuesday that Egypt's ambassador to Saudi Arabia had been instructed to press for the lawyer's release.

At one point, Egyptian Lawyers Syndicate head Sameh Ashour – along with a handful of Egyptian MPs – entered the embassy to discuss the jailed lawyer's fate with Saudi diplomats.