A US embassy security official in Yemen's capital Sana'a was shot dead Thursday while off duty, DPA reported.
Qassem Aqlan, a local employee at the embassy, had worked in the regional security office for 11 years, State Department spokeswomen Victoria Nuland told reporters in Washington.
Nuland disputed regional media reports that Aqlan had been "chief investigator" at the embassy. She said Aqlan had been "head of the foreign service national investigating unit" within the security office - part of security operations staffed by Yemeni employees, not US security personnel.
"He was responsible for routine personnel checks. He was our liaison on security matters to local authorities," Nuland said.
She denied reports by Dubai-based broadcaster Al Arabiya that Aqlan had acted as a coordinator between the Yemeni government and the US in connection with investigations into an attack last month on the embassy by protesters angered by an anti-Islam internet video. Four people died in the protests.
"These initial reports that he was involved in the investigation of the attack were not accurate," Nuland said.
Aqlan was killed while off duty and out with a family member, Nuland said.
Masked gunmen on a motorcycle intercepted Aqlan's car, fired on him and fled, the independent newspaper al-Watan reported. The assailants targeted Aqlan as he was on his way to the embassy in central Sana'a, the paper said.
Nuland condemned the killing as a "vicious act" and described Aqlan as a "dedicated professional."
She declined to discuss suggestions that the killing came exactly one month after the September 11 assault on the US consulate in Benghazi, Libya. The White House said that US officials are in touch with Yemeni officials as they conduct an investigation into Aqlan's death.
Elsewhere, insurgents linked to al-Qaeda executed three abducted government soldiers in the eastern Yemeni province of Mareb, said the independent website Change, citing local sources.
The bodies of the soldiers were dumped near a checkpoint where they had been kidnapped, the report said. It was not reported when the soldiers were kidnapped or slain.
In April, the Yemeni Army launched a high-profile campaign, backed by US drones, against strongholds of Islamist radicals with suspected ties to al-Qaeda.