Four tourists, believed to be South Korean, and a Yemeni man have been killed in an explosion at a tourist site in Yemen.
A Yemeni security official said the explosion happened as the tourists visited the city of Shibam in the southern province of Hadramout.
The official told the Reuters news agency the explosion could have been a terrorist attack, but could also have been ignited by remnants of dynamite from a mine.
The country, one of the poorest outside Africa, has been seen as a stronghold of Islamist militants.
In January 2008, two Belgian tourists were killed in Yemen in an attack blamed on militants, The al Qaeda-linked insurgents have launched frequent attacks on government and Western targets, including a US warship and a French supertanker.
In a separate incident, authorities said they have arrested Abdullah al-Harbi, a Saudi man who was on a list of 85 suspected militants issued by Saudi Arabia in February.
The Saudi list was issued after al Qaeda's wing in Yemen, Osama bin Laden's ancestral home, issued a video on the Internet in which it changed its name to Al Qaeda in the Arabian Peninsula, in an apparent attempt to revive the Islamic militant group in Saudi Arabia.
The leader of the group, a Yemeni, appeared on the video and threatened attacks against Westerners in the region.