Somalia's president says he "wants answers" from South Africa after the brutal murder of a Somali man in Port Elizabeth, Al Jazeera has learned.

The Somali man, 25-year-old Abdi Nasir Mahmoud Good, was stoned to death on May 30 by a mob. The violence was captured on a mobile phone and shared on the internet.

Sheik Mohammed, Somalia's president, called on his South African counterpart Jacob Zuma to "act immediately" to arrest those responsible.

Kamal Gutale, chief of staff in the Somali presidency, told Al Jazeera on Monday: "The president has asked Mr Zuma and his foreign minister to look into the matter and investigate the brutal killing and violence."

The murder is the latest in a number of attacks on Somali immigrants in South Africa. Police are investigating the death but no one has been arrested.

Graphic footage

The Somali presidency said the issue was raised on the sidelines of the Tokyo International Conference on African Development (TICAD) in Tokyo on Sunday, after the Somali community was hit by a series of attacks in South Africa over the last week.

The graphic footage shows the bare-chested Good lying in the middle of a street while a mob pelts him with rocks and boulders as pedestrians and vehicles pass by.

Local media said Good was attacked while trying to protect his shop from looters. He was also stabbed in the violence.

The Somali community in South Africa, which numbers a few hundred thousand, reacted with outrage.

The Somali Association of South Africa (SASA) told Al Jazeera that at least five other Somalis have been injured and about 40 shops have been looted in the four provinces across the country.

Government inaction

"At the time, President Zuma was not aware of the incident and expressed surprise," Gutale said.

The South African president promised to look into the matter, he said.

But SASA said that the South African government has repeatedly failed to act on this and previous attacks on foreigners.

"This is not the first time; this is happening over and over again. The South African government is not taking action, the community is angry and every time this happens, nothing is ever done," said SASA spokesman Ismaeel Abdi Adan.

The South African presidency was unavailable to comment.

The African Centre for Migration and Society at Witwatersrand University in Johannesburg, said in a report released in 2012 that Somali-run businesses suffered disproportionately from crime, including attacks by competing South African traders.

The South African government has said that previous violence against foreigners was a result of criminality and not xenophobia.

In 2008, more than 50 foreign African nationals were killed in a spate of violence against foreign nationals across the country.