A mortar shell was fired overnight in the direction of the French embassy in Yemen, while a car bomb exploded meters away in Sanaa's diplomatic quarter, a police source said Monday.

"The two attacks happened after midnight. There were no victims," the source said.

Renewed clashes between Shiite Huthi rebels and armed tribesmen have killed 13 people in northern Yemen, tribal sources said Tuesday.

Heavy fighting erupted on Monday and continued Tuesday in Wadi Khaywan and Danan, in Amran province, between the rebels and Hashid tribesmen, sources said.

Unidentified gunmen shot dead a law professor who has been representing Shiite Huthi rebels at Yemen's thorny reconciliation talks which are due to end on Tuesday, a security official said.

The killing came as representatives to the national dialogue convened for a final working session, during which President Abrabuh Mansur Hadi set Saturday as a date for a ceremonial conclusion.

An Iranian diplomat was fatally wounded in a drive-by shooting outside the ambassador's residence in the Yemeni capital Saturday, the third attack on embassy personnel in recent months, a medic said.

The medic at Sanaa's Modern German Hospital told Agence France Presse that diplomat, Ali Asghar Assadi, had been "hit in the shoulder, abdomen and stomach."

Gunmen killed a police officer in Yemen's main southern city Aden on Tuesday, shortly after a bomb seriously wounded an intelligence officer, security officials said.

"Unknown gunmen in a vehicle opened fire on a police patrol car in the (central) Dreen district, killing Lieutenant Mubarak al-Ashram and wounding another officer," a police official told AFP.

A Sanaa court on Sunday sentenced to death a Yemeni Al-Qaida suspect for his role in a deadly attack on a security headquarters in Aden in 2011, an official said.

Al-Qaida in the Arabian Peninsula, a franchise of the global jihadist network, is active in Yemen and is seen by the United States as its most dangerous branch.

Air traffic in Yemen stopped for hours on Monday as staff went on strike over a financial dispute with the government.

Five flights scheduled to leave Sanaa International Airport in the morning were grounded, the airport's director general Khaled Ahmed al-Shayef told Agence France Presse, as traffic at other airports also came to a halt.

Two gunmen on a motorbike killed a Belarussian defense contractor and wounded another as they left a hotel in the Yemeni capital on Tuesday, the Russian embassy in Sanaa said.

The gunmen fled after firing on the pair, who were worked under private contract to the Yemeni army, embassy spokesman Nikolai Lyagushin told Russian's Interfax news agency.

Yemeni security forces foiled an attempt by some 300 Al-Qaida inmates to escape after they mutinied in their Sanaa prison, a security official said Wednesday.

The mutiny broke out on Tuesday afternoon when "almost 300 Al-Qaida prisoners, armed with knives and iron bars, attacked prison guards, injuring some of them," the official said, adding that an interrogation officer was among those wounded.

Germany's foreign ministry confirmed Monday that a security official at its embassy in Yemen has been killed but denied reports of an attempted kidnapping of its ambassador.

Earlier reports had said the envoy herself had been the target of a failed abduction attempt Sunday, but the foreign ministry then told Agence France Presse that Ambassador Carola Mueller-Holtkemper was outside the country at the time.