Manama: The number of American nationals detained in Saudi Arabia has risen to nine after four more US citizens were arrested last week on security-related charges.

The website of the Interior Ministry’s prisoners' centre listed four US citizens as having been detained on January 25, two in December and two in November.

One American has been held since March 2007. According to the website, he has been convicted, but his sentence has been appealed.

Five of the detainees have residency permits, three have passports and one has a replacement card.

The site, in line with the ministry's policy, did not give the detainees' full names, but did mention their initials in Arabic.

According to the site, one Briton has been held since June 2012, one French national has been held since February last year and one Chinese national has been held since June. No German, Canadian or Russian nationals have been held.

The Saudi authorities said last week they arrested 33 Saudis, four Yemenis, two Syrians, one Indonesian, one Filipino, one Emirati, one Kazakhstani, one Palestinian and one Pakistani.

Authorities said 5,152 people were now being detained and the figure included those who have been sentenced by courts of law, Saudi news site Sabq reported.

The interior ministry said it had launched the Nafethah (Windows) site to help detainees communicate with their families.

"Nafethah portal was created to help bridge the communication gap between the inmates and their families wherever they are," the ministry said.

"The Communication Window also aims to enable the families of inmates to receive updated information on their status. Nafethah shows the interior ministry's keenness on providing the latest various e-services that meet people's needs and save their time and effort."

The site also provides updated information on the detainees' numbers and nationalities.