The Libyan parliament has elected a businessman, Ahmed Maitig, to become the country's next prime minister, in a controversial vote. Mr Maitig secured 121 votes in a confidence vote on Sunday to confirm his appointment, officials say. But the vote was held in a chaotic session, with several lawmakers expected to challenge the outcome. It comes three weeks after Abdullah al-Thinni resigned from the post following an attack by gunmen on his family. Ahmed Maitig, from Misrata, was sworn in after the vote shown on television. Mr Maitig, 42, was initially reported to have secured 113 votes, falling short of the 120 required. Deputy parliamentary speaker Saleh al-Makhzoum later said Mr Maitig had clinched 121 votes in the 185-seat parliament after voting resumed. Some members are already claiming it was illegal to do so because the chairman had already declared the session for voting over. Mr Maitig, who has the backing of the Islamist bloc in parliament, has been given two weeks to form a government. He beat university professor Omar al-Hassi in an initial vote on Sunday. The two candidates were selected from a group of seven hopefuls in an earlier round. The vote was originally scheduled to take place on Tuesday, but it was interrupted when gunmen stormed the parliament - the General National Congress - forcing the deputies to evacuate. The building has been stormed several times by gunmen over the last year and a half. Libya has been plagued by instability since armed groups toppled Muammar Gaddafi's regime in 2011. One of his immediate challenges will be to tackle the lawlessness and insecurity currently destabilising the country. He is the fifth prime minister to be appointed to lead the country in the past two and a half years. It is unclear how long he will remain in power, although it is likely to be for a short period, our correspondent adds. Elections for a new parliament that will replace the General National Congress are expected later this year, which is also expected to usher in a new cabinet.