The unidentified men, who play for Benghazi's Al-Hilal, "were picked up while they were practising near Garyounes University," said one of the school's security officials.The State Department and Britain's Foreign Office both said they were investigating the matter.
"They were arrested in the company of two Libyans and were freed after being questioned," the source said without explaining why they had been picked up.
The latest incidents comes less than a month after an American teacher was shot to death while jogging in Benghazi, and less than a week after four U.S. military personnel were taken into custody by Libyan authorities and held for several hours before being released.
The AFP noted that four US military personnel were briefly detained on Friday near Sabratha, 60 kilometres (36 miles) west of Tripoli, without any reason being given.
The New York Times reported that the four were attached to the US embassy's security team and had been working on scenarios for a theoretical evacuation of US government employees in the country.
The US ambassador and three other Americans were killed in September 2012 when militants assaulted the US consulate in Benghazi...
Since the revolution that ousted and killed long-time dictator Moamer Kadhafi in 2011, Libya's authorities have struggled to establish security in the country.