Four American military personnel assigned to the U.S. embassy in Tripoli were released after being briefly detained by Libya's Interior Ministry, U.S. officials said Friday.

The four were believed to have been reviewing potential evacuation routes for diplomats when they were detained, the New York Times reported, adding that it was not clear as to how and why they were taken.

"We are seeking to further ascertain the facts and ensure their release," the newspaper earlier quoted Jen Psaki, the U.S. State Department spokeswoman, as saying. "We are in touch with Libyan officials on this issue."

The newspaper said the episode appeared to have taken place in a town southwest of the historic Roman ruins at Sabratha, which is about an hour's drive from the Libyan capital Tripoli.

The Tripoli Post, a Libyan newspaper, quoted a local official as saying the incident occurred when two SUVs were stopped at a checkpoint of Shebaika and each was carrying two foreigners. They were armed and carried communication equipment.

Social media showed a photo of two men sitting on a sofa in an office and posted two State Department IDs, the Tripoli Post said.

Postings on social media allege the four U.S. personnel are spies and question the motive in their venturing away from the capital, the newspaper reported.