Libya's parliament tasked the interim prime minister with forming a new cabinet, weeks after ousting his predecessor for failing to rein in the lawlessness gripping the country.
Prime Minister Abdullah al-Thinni, defence minister under ousted Prime Minister Ali Zeidan, will face the daunting task of bringing former rebel brigades to heel following the 2011 NATO-backed uprising that ended Muammar Gaddafi's four-decade rule.
The country has seen near daily attacks, particularly in the restive east, as well as a challenge from rebels who have blockaded vital oil terminals and a growing political crisis stemming from the interim parliament's decision to extend its mandate.
Thinni "has been confirmed as prime minister and charged with forming a new government" after replacing Zeidan on a temporary basis last month, MP Tahar al-Mokni told AFP news agency.
Omar Hmidan, a spokesman for the General National Congress (GNC), the country's highest political authority, said Thinni was chosen after legislators failed to reach a consensus on other candidates, and was given one week to form a new government.
Thinni had earlier written to parliament asking for more powers and a longer mandate but denied media reports that his government had resigned at a time of deepening turmoil that has hit the North African state's lifeblood oil exports.
"The events that the country is witnessing require quickness in executive decision making. Thus, the interim government will take responsibility only as a government with full authority without interference from the legislative power (General National Congress or its committees)" he said in the letter.
The decision to confirm Thinni was rejected as illegal by some politicians, who said it had not received the required number of votes.
MP Suad Ganur said the decision, which was approved by 42 votes out of 76 members present, was "null and void" because it required 120 votes out of the 200-member assembly.
But Mokni said the larger margin of votes was not necessary because Thinni had already been appointed acting prime minister by 124 votes.
Ali Zeidan ousted
Last month, the GNC ousted Zeidan after the military failed to prevent rebels from sending a tanker loaded with oil out from a blockaded port.
The ship was later captured by US forces and handed over to Tripoli.
After his ouster, Zeidan was replaced by the 60-year-old Thinni, an army colonel who retired in 1997, initially on a temporary basis.
GNC spokesman Hmidan said Thinni would remain in office until the election of a new parliament, the date for which has not been set.
The interim parliament sparked outrage earlier this year when it decided to extend its mandate from February until December. Subsequent protests compelled it to promise early elections and a new electoral law.
Thinni's appointment coincided with the third day of a general strike in Benghazi to protest against the lack of security in the eastern city, cradle of the 2011 revolt, which has seen near-daily attacks in recent months mainly targeting security forces.
Young people in the capital Tripoli had joined the protests Monday, blocking roads with burning tyres, but traffic was back to normal on Tuesday.