An armed group abducted a former Libyan deputy prime minister and newly-elected MP, Mustapha Abu Shagur, in the capital Tripoli on Tuesday, his nephew said.
"Men in three cars kidnapped my uncle from his house and took him away to an unknown destination," Issam al-Naass told AFP.
"Twenty minutes before his abduction, Mr Abu Shagur received a call from a stranger who asked him to leave the house because of imminent danger," he added.
There was no immediate claim of responsibility for the kidnapping.
Abu Shagur was elected a deputy in Libya's June 25 legislative election, in which he stood as an independent candidate.
He is due to take up his post on August 4, at the opening session of the Chamber of Representatives, elected in place of an interim parliament, the General National Congress.
Abu Shagur was deputy prime minister for a year under Abdelrahim al-Kib, who led a first transitional government in the wake of the 2011 uprising that ousted dictator Muammar Gaddafi.
Kidnappings and assassinations of politicians, rights activists and journalists have multiplied in the chaos gripping Libya since Gaddafi's fall.
Ex-prime minister Ali Zeidan was abducted for several hours last October, highlighting the failure of authorities to rein in dozens of militias across the country.