Kenya's Westgate shopping mall reopened on Saturday nearly two years after gunmen from the Somali militant group al Shabaab massacred at least 67 people inside and held out for four days as security forces laid siege to the complex.

Once a totem of Kenya's growing prosperity, the Westgate building has since become symbolic of growing insecurity in the east African nation and President Uhuru Kenyatta's inability to prevent frequent Islamist attacks on Kenyan soil.  

Images beamed across the world during the September 2013 raid dented Kenya's image abroad and scared off tourists, damaging a vital sector of the economy. Kenya's embarrassment was compounded by Westgate security footage which showed soldiers looting the mall after the militants were killed.

Nairobi governor Evans Kidero said the reopening of the mall showed the resilience of the Kenyan people. "I know there will be apprehensions but as a country we are safer than ever and we will continue to work to ensure that our country is safe," he said.

Thousands of people turned up when the doors opened on Saturday morning, and stores and restaurants across the complex were crowded with patrons.

Major Western brands, including Subway, KFC and Converse, have outlets in the new mall along with Kenyan companies such as Nakumatt, a high-end supermarket chain popular with well-heeled locals and expatriate workers.

"When terrorists attack, one of their main aim is to ensure that where they destroy people pull down those buildings and put up memorial parks but in Westgate we refused to do that," said shopper Eric Muluka.

But, in a reminder of the security threat, armed police guarded the entrance to the complex. Inside private security guards in plain clothes patrolled the building, wearing earpieces for communication.

Israeli firm I.R.G. has been put in charge of running security in the reopened mall. New features include explosive detectors, luggage X-rays, scanners to check underneath cars, bollards to prevent car bombs, and bullet-proof guard towers.