An Al-Qaeda-linked Saudi suspect detained in Lebanon is being held in a military hospital because "he is in poor health", a medical official told AFP Friday.

Meanwhile, the army confirmed Majid al-Majid's identity "after a DNA test," a statement said.

A second official familiar with the case said Majid's interrogation "has been delayed because he is in poor health" and that he is being heavily guarded at the Baabda military hospital near Beirut.

The doctor who had been treating Majid before his arrest without knowing who he was said he suffers from kidney failure and requires regular dialysis.

"On December 26, the hospital where Majid was being treated contacted the Red Cross to arrange his transfer to another hospital," said the source.

But before the suspect arrived at the second facility, "the Lebanese army intelligence intercepted the ambulance and arrested Majid," the source said, adding that neither the hospital nor the ambulance teams had prior knowledge of who Majid was.

Majid is the suspected head of the Abdullah Azzam Brigades, which claimed responsibility for an attack in November on the Iranian embassy in Beirut that killed 25 people.

Islamist websites say Majid was revealed to be the leader of the Brigades in 2012, which was designated in the United States as a "terrorist organisation" the same year.

The group was formed in 2009 and is believed to have branches in both the Arabian Peninsula and Lebanon.

The reports come two days after a Lebanese minister told AFP Majid had been arrested by army intelligence.

Saudi Arabia has hailed Majid's detention, and the Iranian embassy in Beirut has requested access to the investigation into the double suicide bombing.

The attack on the embassy came amid rising tension in Lebanon over the role of the Tehran-backed Shiite movement Hezbollah in the war in neighbouring Syria.

Hezbollah and Iran are allied with the Syrian regime, and Hezbollah has sent fighters to battle the uprising alongside government forces.

In claiming the embassy bombing, brigades member Sirajeddin Zreikat warned of more attacks in Lebanon if Hezbollah keeps sending troops to support Syrian President Bashar al-Assad.

In 2009, Lebanon sentenced Majid in absentia to life in prison for belonging to a different extremist group, the Al-Qaeda-inspired Fatah al-Islam.