* Attack in Sanaa is latest in a series on officials
* German embassy closed last month over security fears
* Yemen is battling local wing of al-Qaeda (Adds UNICEF kidnapping)
By Mohamed Ghobari
SANAA, Oct 6 (Reuters) - Gunmen shot dead a German security guard employed by the German embassy in Yemen's capital on Sunday as he was leaving a supermarket, Yemeni security officials said, in an attack they said bore the hallmarks of al Qaeda.
The man was gunned down in Sanaa's Hadda district, where the embassy is located. It was the latest in a series of attacks on foreign and local officials in the U.S.-allied state, which is battling one of the most active branches of al Qaeda.
"We believe that al Qaeda was behind the killing," a Yemeni police source said. Another source said that the guard was killed as he was leaving the store to go to his car.
Pan-Arab news channel al-Arabiya reported that the guard had been shot dead as the assailants tried to kidnap the German ambassador Carola Mueller-Holtkemper, who escaped.
Two Yemeni officials said they were unable to confirm the report of the attempted kidnap. Embassy employees in Sanaa and the German Foreign Ministry in Berlin declined to comment.
Mueller-Holtkemper had only recently arrived in Yemen and presented her credentials to Yemeni authorities less than a week ago, a statement on the embassy's website showed.
In a separate attack on Sunday, kidnappers seized an African employee of the United Nations children's agency UNICEF as he was travelling from the Sanaa to the Red Sea coastal town of Hudaidah, a UNICEF official in Sanaa said.
Yemen-based al Qaeda in the Arabian Peninsula (AQAP) has attacked several Western targets, including airliners, and is believed to have been behind a series of killings of foreign and local officials in the country since 2011.
In November last year gunmen shot dead a Saudi diplomat and his Yemeni bodyguard in Sanaa in an attack believed to be the work of the group. A month earlier, masked gunmen shot dead a Yemeni man who worked in the security office of the U.S. Embassy.
Germany was one of several Western countries which shut their Yemen embassies in early August after a U.S. warning of a possible major militant attack in the Middle East. The mission reopened after a two-week closure.
The U.S. embassy in Yemen was attacked in September 2012 by demonstrators angry at a film they said was blasphemous to Islam. Hundreds of Yemenis broke through the main gate of the heavily fortified compound, smashed windows of security offices outside the embassy and burned cars.
On Sunday AQAP said in a statement it was behind an attack on an army base in the southeast of the country last week in protest at the army's cooperation with the United States and vowed to continue its "holy war" against Yemeni forces.
Militants took advantage of political chaos in Yemen during the Arab Spring uprising in 2011 to seize control of some towns and surrounding areas in the south of the country.
They were beaten back by Yemeni forces with assistance from the United States and dispersed into smaller groups spread across the south of the country. (Additional reporting by Boris Berner in Berlin, Writing by Sylvia Westall; Editing by William Maclean and Andrew Roche)