Victims of the massacre were buried on Thursday while forensic experts from around the world, including Germany, Britain and the US continued their investigation at Nairobi's Westgate mall. The team was conducting fingerprint, DNA and ballistics tests.

Searching the vast complex for bodies and possible clues could take at least a week to complete, according to Kenyan Interior Minister Joseph Luku.

At least 67 people were killed during a four-day siege that began when gunmen stormed the shopping center on Saturday. Police have stressed that the death toll could change and the Kenya Red Cross has said 61 people still remain unaccounted for. Five of the suspected attackers were killed during the siege and 11 were detained, officials said. The al-Qaeda-linked Somali group al-Shabab has claimed responsibility for the attack.

Images released by the army show the immense destruction the building suffered, including a large section that collapsed where the militants are believed to have made their last stand. Bodies belonging to victims and the attackers may be buried in the rubble.

'Red alert' for 'white widow'

The international police agency Interpol on Thursday issued an internationally wanted persons alert, or "red alert" for Samantha Lewthwaite, a British citizen dubbed the "white widow." The alert, made at the request of Kenya, did not mention the siege at Westgate. British media speculated about her being a possible suspect in the attack after Kenya's foreign minister said a British women was among the attackers, but there has been no evidence linking her to it.

Lewthwaite is wanted by Kenyan authorities over her alleged involvement in a holiday resort bomb plot.

She is also believed to use the alias "Natalie Webb" and was married to one of the suicide bombers who carried out the deadly 2005 attack on London's Underground subway system.

Border towns attacked

Earlier on Thursday, militants attacked the Kenyan border town of Mandera, killing two police officers and injuring three others, said regional police chief Charlton Mureithi, adding that 11 vehicles were also destroyed.

Al-Shabab claimed responsibility for the raid.

Wednesday night militants also attacked the town of Wajir, 390 kilometers (240 miles) southwest of Mandera, killing one person and wounding four.

dr/pfd (AP, AFP, Reuters)