Unidentified gunmen shot dead three tourists from Saudi Arabia in an attack Monday in Niger's remote western desert, officials said.
Three other Saudi citizens were also wounded in the assault, Niger government spokesman Mamane Kassoum Moktar told The Associated Press.
Saudi Deputy Foreign Minister Khaled bin Saud told Saudi-owned Al-Arabiya TV the tourists were leaving Niger for neighboring Mali when they were attacked around dawn after stopping their vehicle to perform morning prayers.
It was not clear what sparked the violence, but local insurgents, bandits and members of al-Qaida's Algeria-based North Africa branch are believed to be active in the remote deserts near the Mali frontier.
Asked if they suspected al-Qaida was behind the attack, Saud said the group is active in the area "but we have no proof" they were involved.
"It appears to us so far that it was a robbery," Saud said, adding that authorities in Niger were in contact with their Saudi counterparts.
Moktar also declined to speculate on whether al-Qaida was behind the attack. He said the assailants were traveling in a four-wheel-drive when they fled, and that police and army forces had been dispatched to track them down.
Moktar said two guides from Mali who had been escorting the Saudis were found by police with their hands tied on Monday in Ayerou village, near where the attack occurred.
In April, kidnappers in Niger released four foreign hostages who had been held for months, including the United Nations' former special envoy to Niger, Canadian diplomat Robert Fowler.
Niger's president blamed Fowler's abduction on a rebel group of ethnic minority Tuareg nomads who have waged a low-level insurgency for years. But Al-Qaida's North Africa branch claimed responsibility for that kidnapping.
Al-Qaida in Islamic North Africa is an Algeria-based group that joined Osama bin Laden's terrorist network in 2006 and conducts dozens of bombings or ambushes each month. The group operates mainly in Algeria but is suspected of crossing the country's porous desert borders to spread violence in the rest of northwestern Africa.
On Monday, al-Qaida claimed responsibility for kidnapping two Italians earlier this month in Mauritania, which borders Mali and is located on the northwestern fringe of Africa. Rome's foreign minister said it was likely the hostages were in the hands of the radical Islamist group.
Associated Press Writer Sarah El Deeb contributed to this report from Cairo.