The Somali-based Islamist armed group al-Shabab's blatant disregard for life in its attack on a Nairobi shopping centre on Saturday is a despicable affront to basic human rights, Amnesty International said.
"Amnesty International stands in solidarity with the people of Kenya in the wake of these callous and despicable attacks," said Salil Shetty, Secretary General of Amnesty International.
"Our thoughts and sympathy go out to all those affected by this violence. We welcome President Uhuru Kenyatta's commitment to investigate the attack and bring the perpetrators to account.
"We urge the Kenyan authorities to ensure that the investigations are prompt, thorough, independent and impartial. Any suspects arrested should be brought to trial in line with international standards."
According to the Kenya Red Cross, as of Monday at least 62 people had died and at least 175 had been injured after a group of 10 or more armed fighters stormed Nairobi's Westgate shopping mall on Saturday.
The Somali Islamist group al-Shabab has claimed responsibility for the attack, denouncing the Kenyan armed forces' military intervention against the group within Somalia.
Many foreign nationals also died in the attack - Westgate mall is frequented by the elite of Kenyan society as well as many internationals in the country.
Among those reportedly killed was the renowned Ghanaian poet and former diplomat, Dr. Kofi Awoonor. Amnesty International had campaigned on the poet's politically motivated trial in the mid-1970s.
On Monday morning, the Kenyan defence forces continued a major military operation to free a number of hostages believed to be still inside Westgate. In a press conference this afternoon, the Interior Minister said that the security forces had gained control of all floors of the building and that most hostages had been rescued.
"This despicable tragedy touched on people not only in Kenya but much further afield - and the international community is in solidarity in the wake of the attack," said Shetty.
Al-Shabab seeks to impose shari'a law within Somalia and remains engaged in armed conflict in central and southern Somalia with the African Union Mission in Somalia (AMISOM) and Somali forces.
The Kenya Defence Forces first deployed a military force into Somalia in 2011 following a spate of attacks in Kenya, including the kidnapping of two Spanish aid workers with Médecins Sans Frontières from Dadaab refugee camp. There are currently 4,000 Kenyan troops in Somalia, now a part of AMISOM.
Al-Shabab has in the past expressed its intent to carry out reprisal attacks in Kenya. Attacks using hand-grenades and other explosives have been carried out on Kenyan territory, often thought to be attacks by al-Shabab and al-Shabab sympathisers, but in recent years there has been nothing of the scale of Saturday's attack.
Amnesty International has worked on the human rights situation in Kenya for more than four decades has an active national Section there. The organization is also due to open a regional office in Nairobi in the coming months.