A French mother and her daughter were killed in Saturday's attack on the Westgate shopping mall in Kenya's capital Nairobi, French officials said on Sunday.

"Two of our compatriots were cowardly attacked and executed in the parking lot of the shopping center," said Helene Conway-Mouret, the minister in charge of French citizens living abroad.

The tragedy was staged by Somali Islamist militants who launched a deadliest attack on the popular shopping mall in Nairobi in retaliation for the East African country's military action against the Somali militants group Al-Shabaab.

So far, at least 68 people have been killed and 175 others wounded in the attack.

The French minister said there were seven French citizens at the shopping mall when Al-Shabaab militant began their operations. Howeve, five of the French citizens had flee the center. One was injured by bullet and admitted to hospital but was not "in danger," Conway-Mouret told French channel BFM TV.

On Saturday night, French President Francois Hollande "condemns the cowardly attack in the strongest terms and shares the pain of the family of our compatriots", the president office said in a statement.

Latest media reports said up to 15 gunmen are still holding a number of hostages inside the shopping mall.

Nearly 50 people remain unaccounted for in tense standoff between Kenyan security forces and Al-Shabaab suspects, according to the Kenya Red Cross sources.

In another development on Sunday, the international police organization Interpol offered to deploy an Incident Response Team consisting of specialized forensic officers, anti-terror experts and analysts after the mall attack in Kenya.

Interpol said, if requested, it can issue one of its color-coded international notices to alert law enforcement around the world about the modus operandi behind the attacks.