Riyadh: Nine Americans are among 33 suspects detained on terrorism charges in Saudi Arabia over the past week, the English-language daily Saudi Gazette reported on Sunday citing an unnamed source.

It reported that four Americans were detained on Monday and another five in the following days, along with 14 Saudis, three Yemenis, two Syrians, an Indonesian, a Filipino, a United Arab Emirates citizen, a Palestinian and a citizen of Kazakhstan.

The American embassy did not immediately respond to a request for comment.

Saudi Arabia in 2014 declared Daesh a terrorist organisation and has detained hundreds of its supporters. The group, which controls territory in Iraq and Syria, has staged a series of attacks in the kingdom.

On Friday an attack at a Shiite mosque in Saudi Arabia’s Al Ahsa district in Eastern Province killed four people and injured 18, the latest in a string of attacks claimed by Daesh that have left over 50 dead in the past year.

The website of the Interior Ministry’s militant rehabilitation centre listed four US citizens as having been detained on Jan 25 and four more over the previous three months.

It did not yet list any more recent detentions.

The Interior Ministry spokesman pointed Reuters towards that website, which gives information on all people detained as militant suspects, but gave no further comment.

The ministry on Saturday identified one of the attackers in Al Ahsa as 22-year-old Abdul Rahman Al Tuwaijri, a Saudi citizen, who detonated an explosive vest outside the Imam Rida mosque in the Mahasen district of Hofuf in Al Ahsa.

A 27-year-old was also arrested wearing an explosive vest and carrying hand grenades after members of the mosque’s congregation seized him after he fired shots at them during the attack, the ministry said.

Attacks by supporters of Daesh in Saudi Arabia include two bombings and two mass shootings at Shiite mosques.

A mosque used by Sunni security services was also bombed.