Kenyans Saturday marked a week since Islamist gunmen stormed a Nairobi mall in an attack that shocked the nation, but confusion remained over the fate of 61 people still reported missing.

Kenyan and foreign investigators continued to comb the carcass of the upscale Westgate mall for clues on the perpetrators of the 21 September raid and ensuing four-day siege.

Sixty-seven people have so far been confirmed killed in the attack, the worst in Kenya since the 1998 US embassy bombing.

But there was no fresh information on bodies believed to still be trapped in the rubble from the partial collapse of the complex's rooftop car park towards the end of the siege.

"When we went in the first few hours of that fateful Saturday, up in the car park... we found survivors but we also found lots of dead bodies," Kenyan Red Cross chief Abbas Gullet said.

"So common sense will tell you respond to the survivors, get them out to safety, treat them, let them go to hospital you can get the bodies later.

"And that's what happened. So now we have bodies there," he said.

The Red Cross says 61 people are still reported missing but the interior minister has said there could only be an "insignificant" number of bodies still trapped in the wreckage.

Kenyans have shown signs of impatience over a number of other questions that have remained unanswered since President Uhuru Kenyatta announced the end of the siege on Tuesday.

Survivors, the families of the dead, media and members of the public also want to know who the attackers were, why the car park collapsed and whether the state was adequately prepared.