NAIROBI, Kenya (CNN) -- A number of Kenya's Cabinet members and defense officials were warned about the possibility that the terror group Al-Shabaab was planning to carry out a Westgate-style attack a year before gunman stormed the Nairobi mall, according to several police and intelligence sources.

The warnings were made by the country's National Intelligence Service as part of regular situational reports given to cabinet members, the inspector general of police, members of the National Security Advisory Council and military intelligence.

CNN has seen an electronic version of those reports, which contain an extensive list of terror threats from several regions across Kenya over an extended period, but they also specify Al-Shabaab posed a threat to several targets, including Westgate Shopping Mall.

The news about the intelligence warnings come amid revelations that the mall favored by Westerners and tourists was long-considered a possible terror target.

CNN has also learned that the Westgate mall attackers tortured some of the hostages.

Military doctors said militants severed hands, cut off noses and, in some cases, hanged hostages. CNN has seen photographic evidence of one dead victim with a hand amputated.

Inquiry begins

Members of Parliament are expected Monday to begin grilling intelligence bosses, including the head of the National Intelligence Service, over the apparent intelligence failures.

The news of the intelligence warnings follow the September 21 terror attack at Westgate that resulted in a four-day standoff that left at least 67 people dead and parts of the shopping center destroyed. Thirty nine are still unaccounted for, possibly buried beneath the rubble.

The attackers claimed to be members of the Somali-based Al-Shabaab.

Al-Shabaab itself made statements claiming responsibility, including saying on Twitter that it sent the gunmen in retaliation for Kenya's involvement in an African Union military effort against the group, which is al Qaeda's proxy in Somalia.

Kenyan forces killed five terrorists, and 11 others are in custody over possible links to the attacks, President Uhuru Kenyatta has said.

Immense work remains

But an immense amount of work remains to learn how Al-Shabaab, a terror group thought to be badly bruised by recent losses in its Somalian homeland, was able to pull off such a well-coordinated and brazen attack.

Last year, the Kenyan military was part of a peacekeeping force that defeated Al-Shabaab forces to liberate the key Somali port of Kismayo.

Since Kenya launched attacks against Al-Shabaab in Somalia in 2011, the group has hurled grenades at Kenyan churches, bus stops and other public places.

It was the deadliest terror attack in Kenya since al Qaeda blew up the U.S. Embassy there in 1998, killing 213 people.

Terrorism experts say the attack bears eerie similarities to the 2008 siege of a hotel in Mumbai, India -- another upscale target with Western appeal. Lashkar-e-Taiba, a Pakistani terrorist group that attacked the hotel for more than three days, killing 166 people.

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