WASHINGTON - The Pentagon confirmed Tuesday that US forces on Sunday captured a key figure suspected in the attacks on US facilities in Benghazi, Libya, in September 2012.

The US Consulate in Benghazi is seen in flames during a protest by an armed group said to have been protesting a film being produced in the United States in this September 11, 2012 file photo. Ahmed Abu Khatallah, a key suspect in the 2012 attack on the US diplomatic compound in Benghazi, Libya, is being held on a US ship following his capture over the weekend by US special operations forces, a US official said on June 17, 2014. The official, speaking on condition of anonymity, said the suspect was apprehended on the outskirts of Benghazi in a secret operation.

The suspect, Ahmed Abu Khatallah, is in US custody in a secure location outside of Libya, said Rear Admiral John Kirby, spokesman of the Defense Department.

There were no civilian casualties related to the operation over the weekend, and all US personnel involved in the operation have safely departed from Libya, Kirby said in a statement.

The Washington Post reported Tuesday that the suspect was captured near Benghazi by American troops working alongside the Federal Bureau of Investigation following months of planning.

In a statement released by the White House, US President Barack Obama said he had authorized the operation in Libya to detain Khatallah Sunday.

"The fact that he is now in US custody is a testament to the painstaking efforts of our military, law enforcement, and intelligence personnel. Because of their courage and professionalism, this individual will now face the full weight of the American justice system," Obama said.

US Secretary of State John Kerry also said in a statement that Sunday's operation "is a clear reminder to anyone who dares do us harm that they will not escape with impunity."

According to officials who spoke to The Washington Post on condition of anonymity about the still-secret operation, Khattala was "en route" to the United States to be arraigned in Washington, DC Last year, the US Attorney in the District filed charges against Khattala and at least a dozen others in connection with the Benghazi attacks.

The Sept. 11, 2012 assault on the US diplomatic compound in Benghazi left four Americans dead, including US Ambassador to Libya J. Christopher Stevens.

The State Department designated Khattala as a terrorist in January, calling him a "senior leader" of the Benghazi branch of the militant group Ansar al-Sharia, which was also designated a terrorist organization.

Asked whether Libya had approved the Sunday raid, a US official told The Washington Post: "I am not going to get into the specifics of our diplomatic discussions, but to be clear: This was a unilateral US operation."

"We have made clear to successive Libyan governments our intention to bring to justice the perpetrators of the attack on our facilities in Benghazi," the paper cited the official as saying. "So it should come as no surprise to the Libyan government that we would take advantage of an opportunity to bring Abu Khatallah to face justice."

Republicans have charged that the White House has failed to secure the US diplomatic mission in Benghazi, attempted to cover up what actually occurred on the night of the attacks, and mishandled the subsequent investigation. A select committee has been set up in the House of Representatives to further investigate the episode.