TEL AVIV – Saudi Arabia has arrested four Americans accused of joining the Islamic State, sources told the country’s Al Jazirah newspaper.

The paper, one of four leading daily publications in the kingdom, reported on Sunday that the Americans were arrested as part of a broader anti-terrorist operation in which a total of 377 people have been detained over the past 57 days on suspicion of joining ISIS.

Also arrested in the anti-terror sweeps were four Belgians, 29 Syrians, 26 from both Yemen and Somalia, three Egyptians, two Turks, three Palestinians, and six each from Sudan, Ethiopia, Afghanistan, and Pakistan, the newspaper reported.  287 of the suspects were Saudis.

Al Jazirah did not provide any further details about the arrested Americans.

The Saudi embassy in Washington acknowledged receiving a Breitbart Jerusalem request for comment but did not reply before press time.

FBI chief James Comey said in July that over 200 American citizens have traveled or attempted to travel to Syria to fight in the country’s civil war.

A study released last month by the New America think tank examined a sampling of 83 Americans who traveled to Syria or Iraq to fight, attempted to do so, or provided support to the jihadists fighting there. The study found that their average age was 24, more than one fifth were teenagers, and more than one in six were women.

In August 2014, BuzzFeed documented the case of Moner Muhammad Abusalha, a US citizen born to a Palestinian father and an American mother who became the first American suicide bomber in Syria.  The 22-year old blew himself up when he drove a truck bomb into a restaurant filled with Syrian government soldiers.