A senior member of Somalia's Shebab insurgents was indicted Tuesday in New York on terror charges after being interrogated on a US warship for two months, officials said.

Ahmed Abdulkadir Warsame was captured by the US military in the Gulf on April 19 and kept secretly aboard a US Navy ship at sea, where he faced questioning by US interrogators "for intelligence purposes," according to US officials.

His case, the first known example of President Barack Obama's administration secretly holding and interrogating a terror suspect, provided insight into how the administration plans to question and try detainees outside war zones after closing the CIA's secret prison network.

A US official said Warsame's questioning was conducted under the rules of the US Army Field Manual, which places strict limits on interrogation techniques.

Members of the High Value Interrogation Group -- comprised of CIA, FBI and Defense Department staff -- interrogated him, the official told AFP on condition of anonymity.

The official said Warsame provided "useful information," without providing further details.

Late into his detention, Warsame was informed of his Miranda rights -- that he cannot be forced to incriminate himself and that anything he said could be used against him -- but agreed to keep talking to law enforcement officials for seven days after that, the Justice Department said in a letter to the court.

He was turned over to the FBI before being flown to New York.

Described as a Somali national in his mid-twenties, Warsame was indicted in US District Court in Southern Manhattan on charges of providing material support to the Shebab and Al-Qaeda in the Arabian Peninsula, the terror group's branch headquartered in Yemen.

He was accused of serving as a go-between between the two groups, providing them with both money and training, and faces a life sentence if convicted on the terror and weapons charges.

AQAP is suspected of being behind a string of plots targeting the United States, including a Christmas 2009 attempt to blow up a US airliner that was claimed by the group.

And Warsame's nine-count indictment came as US officials express increasing concern about growing ties between Shebab and Al-Qaeda, as well as instability in Yemen and Somalia, among the world's poorest countries.

"As alleged, Ahmed Warsame was a conduit between Al-Shebab and Al-Qaeda in the Arabian Peninsula -- two deadly terrorist organizations -- providing material support to them both," said Preet Bharara, US attorney for the Southern District of New York.

"Protecting Americans from the threat of terrorism is, and always will be, our number one priority."

According to the indictment, Warsame provided material support support to the Shebab from at least 2007 until April 2011 that resulted in the death of at least one person.

He is also said to have fought on behalf of the Shebab in Somalia in 2009 and provided explosives, weapons, communications equipment, expert advice, assistance and training to the group, as well as used destructive weapons such as machine guns and an AK-47 semi-automatic assault weapon.

From about 2009 to April of this year, he provided money, training, communications equipment, facilities and personnel to AQAP, the indictment added. He also allegedly received explosives and other military-type training from the Al-Qaeda branch in Yemen last year and this year.

He was further said to have brokered a weapons deal with AQAP on behalf of the Shebab, and taught other insurgents how to make explosives, destructive devices and weapons of mass destruction.