* Tribesmen had occupied ministry demanding jobs
* Senior security official survives second attack
* Oil pipeline, closed for months due to attacks, reopens (Adds assassination attempt on security official)
Yemeni tribesmen agreed on Monday to vacate the Interior Ministry after storming it the day before in a protest for jobs, an official said - an incident that highlighted the ongoing turmoil in a country where al Qaeda militancy has alarmed world powers.
In a further sign of instability in the Arabian Peninsula country, a security official survived an assassination attempt when a bomb placed under his vehicle was detonated remotely in the southern port city of Aden.
Yemen is struggling to establish order following the ouster of President Ali Abdullah Saleh in February after a year of protests against his rule.
An Interior Ministry source said it had persuaded the 100 tribesmen, seen as loyal to former President Saleh, to vacate the ministry, in the capital, Sanaa. The tribesmen were demanding to be enlisted in the police force.
"The president (Abd-Rabbu Mansour Hadi) formed a committee to negotiate," the source said.
"They were persuaded to end the occupation in return for a promise to respond to their demands."
In Aden, Colonel Taha Hussein al-Sobaihi was rushed to hospital after the failed assassination - the second attempt on his life in one year.
Yemeni authorities were also hunting the abductors of an Italian embassy security officer, a member of the Carabinieri police, kidnapped near his embassy in Sanaa on Sunday.
In March, the Saudi deputy consul in Aden, Abdallah al-Khalidi, was kidnapped by al Qaeda-linked militants who demanded the release of women detainees from Saudi prisons.
During the uprising that toppled Saleh, militants associated with al Qaeda strengthened their position in areas of south and east Yemen, further testing central government control in a country riven with tribalism and regionalism.
Tribesmen often kidnap foreigners and bomb oil and gas pipelines as a way to press demands on authorities.
Yemen delivered its first oil shipment from the Maarib pipeline to its Aden refinery on Monday, after a nine-month halt caused by tribal attacks that left Yemen relying on imports and Saudi fuel donations, a refinery official told Reuters.
Yemen's location next to leading oil exporter Saudi Arabia and astride key world shipping routes has heightened regional and Western concern over the security situation.
The disorder has alarmed the United States, a backer of Saleh who has sought to ensure that his successor makes fighting al Qaeda his priority. Yemen now ranks alongside Pakistan and Afghanistan for U.S. policymakers concerned with the spread of al Qaeda networks. (Reporting by Mohammed Ghobari; Writing by Andrew Hammond and Mirna Sleiman; Editing by Alessandra Rizzo and Robin Pomeroy)