SANAA, March 17 (Reuters) - A suicide bomber behind a deadly attack that killed four South Korean tourists in Yemen was trained in lawless Somalia, just across the busy Gulf of Aden shipping route, a Yemeni security official said on Tuesday.
The bombing, which is likely to further damage the impoverished country's nascent tourism sector, came after repeated calls by al Qaeda leaders for attacks on non-Muslim foreigners in the Arabian Peninsula.
Violence in Yemen has affected foreign firms developing its oil and gas sector, while attacks on foreigners -- including kidnappings by tribesmen -- have hit tourism, diplomats say.
Yemen, the ancestral homeland of Osama bin Laden, has for years been battling al Qaeda and similar groups, but no group has yet claimed responsibility for Sunday's attack.
The official identified the bomber as Abdel Rahman Mehdi al-Aajbari and said he had trained in Somalia, a failed Horn of Africa country that Western security services fear could be a base for al Qaeda-linked militants.
Aajbari had left his family home in the Yemeni province of Taiz around two months ago, he said.
In a letter to his mother delivered by one of his fellow fighters, Aajbari wrote that his family would never see him again and that he believed he was on the "true path", the official said.
Yemen agreed in January to host the former Somali president, Abdullahi Yusuf, after he resigned in December.
Yusuf had been accused by donor countries and regional governments of being an obstacle to U.N.-hosted peace talks.
Tens of thousands of Somali refugees arrive in Yemen each year, making the perilous sea crossing to escape instability in their own country. Yemen's government is also struggling against an insurgency in the north and the potentially disastrous economic impact of dwindling water and oil reserves.
Analysts say Yemen's multiple challenges put it in danger of becoming a "failed state", whose own problems could spill across the border into Saudi Arabia, the world's top oil exporter, which has been fighting its own campaign against al Qaeda.
Yemeni authorities have rounded up dozens of militants believed to be linked to al Qaeda, which has launched frequent attacks on government and Western targets in Yemen, including the U.S. embassy in Sanaa, a U.S. warship and a French tanker.
Sunday's blast occurred as Korean tourists were visiting Shibam, a UNESCO World Heritage site dubbed the "Manhattan of the desert" for its 16th-century tower houses.
In January 2008, two Belgian tourists were killed in Yemen in an attack blamed on al Qaeda-linked militants.
Yemen joined the U.S.-led war against terrorism following the Sept. 11, 2002 attacks on U.S. cities but is still viewed in the West as a haven for Islamist militants. (Reporting by Mohamed Sudam; Writing by Lin Noueihed)
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