NEW YORK (AFP) - US Secretary of State John Kerry said on Sunday that the deadly mall siege in Kenya had highlighted the gravity of the threat posed by Somali militants.

Mr Kerry said he had spoken with Somalia's foreign minister and ambassador to Washington earlier in the day about the attack on a Nairobi shopping mall.

"It represents the seriousness and the breadth of the challenge we face with ruthless and completely reckless terrorists," Mr Kerry told reporters as he started a meeting in New York with Egypt's Foreign Minister Nabil Fahmy.

"It's an enormous offence against everybody's sense of right and wrong." Al-Qaeda-linked Shebab fighters have claimed responsibility for the attack on the Nairobi mall in which at least 68 people have been killed and about 200 wounded.

Mr Kerry said he spoke with Somalia's Foreign Minister Fawzia Adan and its ambassador to Washington, Elmi Duale, about the crisis.

Following battlefield gains by an African Union force and Somalia's transitional government army against Shebab, the United States has been considering reopening its embassy in Mogadishu. The embassy has been closed since 1991.