Libyan Prime Minister Shukri Ghanem - seen as one of the key architects of the end of decades of international isolation - has been sacked.
Prime Minister Ghanem was popular with the growing private sector
He was also known for his controversial attempts at free market reform.
He will take charge of Libya's national oil company, and be replaced by his deputy, Baghdadi Mahmudi.
Libya's parliament announced the sacking as part of a major cabinet reshuffle - the first since 1994.
Correspondents say Mr Ghanem's policies were popular with business people but opposed by local committees responsible for carrying out government policy.
Mr Ghanem, who studied in the US, had been in the job since June 2003.
But his gradual privatisation of state-owned companies, as well as the decrease in government subsidies to electricity and petrol, put him at odds those of his parliamentary counterparts loyal to socialist ideals.
Mr Ghanem once said they should either allow him to implement change or let him go.
His calls seem to have been heard, says the BBC's correspondent in Tripoli, Rana Jawad.
In his new role he will be in complete control of the oil and gas sector.
His successor, Dr Mahmudi, is the former health minister and a medical doctor by profession.