Gunmen who massacred at least 67 people in Kenya's Westgate mall in September were special suicide commandos, Somalia's Shebab insurgents said Tuesday, rubbishing reports the men had tried to escape.

Members of a "martyrdom brigade", the gunmen were "brothers who have volunteered to enter into enemy ranks and cause havoc before being killed by the enemy," the Al-Qaeda-linked Shebab said in the latest issue of their online magazine.

While not specifically saying they had died, the Shebab dismissed initial reports by Kenya's army chief, Julius Karangi, that the men had attempted to flee.

"Karangi even had the audacity to claim that the martyrdom-seeking mujahedeen were seeking to abscond and escape from the mall," the magazine read.

The magazine, released Tuesday via extremist websites, is a special edition dedicated to the four-day siege at Westgate.

Slickly produced and written in both English and East Africa's Swahili language, it is crammed with gruesome photographs of the attack, and gloating messages lauding the success of the massacre.

"Westgate was not a fight, it was a message," the magazine read, quoting Shebab spokesman Ali Mohamed Rage. "The real fight is on the way."

It did not name or say how many gunmen there were, but police believe there to have been only four attackers, and not the dozen that security forces had initially reported.

Interpol is assisting Kenya in trying to identify four bodies suspected to be those of the gunmen.

However, media have previously speculated the gunmen may have escaped in the chaos of the fighting, although security sources say they died in a final stand off with Kenyan commandos, who ended the fight by firing anti-tank rockets that sparked a fierce fire.

Witnesses in the mall described how the fighters stormed the crowded complex, firing from the hip and hurling grenades at shoppers and staff.

The Kenyan Red Cross has said some 20 people are still missing, and there are fears more bodies could be found in the wreckage of the mall.

"Westgate was meant to send a message to Kenyans: get out of Somalia and stop your aggressions against Muslims," the magazine read.