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NEW: State Department and White House officials say they can't confirm detention reports

The Saudi Interior Ministry says four Americans were detained in January

They're on the ministry's list of detainees, which does not detail alleged crimes

CNN  — 

Four Americans were detained in Saudi Arabia last week on suspected terror offenses, bringing the total number of Americans in Saudi jails to nine, according to an online list of inmates posted by the Saudi Interior Ministry.

Four U.S. citizens were detained January 25 and four others were detained in November and December, according to the site, which describes their cases as under investigation.

A ninth American, imprisoned since 2007, was convicted, according to the ministry, which did not say what the conviction was for or the length of the sentence. The case is subject to appeal.

The ministry only provided the detainees’ initials, and did not give information about exactly what their alleged crimes are.

The list includes 5,152 detainees – mostly Saudis – held or investigated for terror-related acts, the Interior Ministry said. But some are held without being charged, the ministry said.

State Department and White House officials said Monday that they couldn’t confirm the reports of Americans detained in Saudi Arabia.

“I don’t have anything definitive with respect to the actual truth of these reports,” State Department spokesman John Kirby said. “What I can tell you is that we’re working closely with Saudi authorities to try to figure this out and to iron it out.”

A U.S. Embassy official in Riyadh told CNN the embassy is “aware of those reports alleging that several US citizens were detained.”

“We are looking into it and the Department of State takes its obligation to assist U.S. citizens abroad very seriously,” the official said. “If it did concern U.S. citizens, due to privacy considerations, we would have no comment on their specific identities or situations.”

CNN’s Catherine E. Shoichet and Jennifer Rizzo contributed to this report.