WASHINGTON, Oct 30 (Reuters) - U.S. forces have captured a militant who is believed to have played a role in a 2012 attack on a U.S. diplomatic compound in Benghazi, Libya, that killed U.S. Ambassador Christopher Stevens and three other Americans, U.S. officials said on Monday.

The officials, speaking on the condition of anonymity, said that U.S. Special Operation Forces captured the militant in Libya in the past few days.

Two of the officials identified him as Mustafa al-Imam and said he had played a role in the attack and the ambassadors death.

The officials said the man was now in the custody of the Department of Justice and being transported back to the United States by the military.

They added that the operation was authorized by President Donald Trump and had notified the U.N.-backed Government of National Accord.

In a statement, Trump said al-Imam will face justice in the United States for his alleged role in the September 11, 2012 attacks.

Attorney General Jeff Sessions said al-Imam was now in custody and the United States would continue to investigate and identify those who were involved in the attack.

The appropriate Congressional committees and the families of the Americans killed in the 2012 attack had also been notified, the officials said.

The attack on the embassy was the topic of numerous congressional hearings, with Republican lawmakers critical of the way in which then-secretary of state Hillary Clinton responded to the attack.

Earlier this month, U.S. prosecutors opened their case against the suspected ringleader, Ahmed Abu Khatallah.

Khatallah had been awaiting trial since 2014, when he was captured by a team of U.S. military and FBI officials in Libya and transported on a 13-day journey to the United States aboard a Navy vessel.

Militants have exploited chaos following Muammar Gaddafis 2011 downfall.

Islamic State took over Sirte in early 2015, turning it into its most important base outside the Middle East and attracting large numbers of foreign fighters to the city.

Islamic State militants has shifted to desert valleys and inland hills southeast of Tripoli as they seek to exploit Libyas political divisions after their defeat in Sirte.

The United States has been carrying out strikes against the militant group in Libya, striking more than a dozen militants in September.

(Reporting by Idrees Ali; Editing by Grant McCool and Marguerita Choy)