High poverty levels and slow police reaction exacerbated the current xenophobic crisis, ANC deputy president Kgalema Motlanthe said on Thursday.

"When people live in squalid conditions like that it takes only one incident [to spark violence]. The response of our law enforcement was delayed in my view," he told an International Media Forum in Johannesburg.

"The area where this problem started should have been cordoned off immediately, but the delay encouraged people in similar environments to wage similar attacks.

"The issue really is, these people living in these squalid conditions have to fight for every square metre... They have real, real challenges. Some of them are so poor, living simply means not dying," said Motlanthe.

Their "levels of desperation" were high, he added.

"One single incident can spark a reaction... The first challenge is to bring it under control."

Motlanthe said the majority of Zimbabweans living in South Africa were "people with better basic education" while Mozambicans have skills as builders.

"Therefore these illicit attacks are from our own South African brothers and sisters who have not had the opportunity to acquire skills."

He said the army had been deployed to "cover the peripheries" of the affected areas.

President Thabo Mbeki on Wednesday signalled the go-ahead for army involvement in the xenophobic attacks that have left more than 40 people killed and displaced 17 000.

The violence started in Alexandra on 12 May and then spread to other Johannesburg townships including the East Rand, and isolated incidents of xenophobia have also occurred in KwaZulu-Natal, Mpumalanga and North West province.

Sapa