Abuja (AFP) - Nigeria's President Muhammadu Buhari on Tuesday vowed to streamline the country's oil and gas sector to boost revenues and get Africa's biggest crude producer on a firmer financial footing.

Both measures come as Buhari tries to fulfil his pre-election pledge to tackle widespread graft and waste, particularly in the oil sector which provides most of the government's revenue.

He told the heads of oil major Exxon-Mobil and the Nigeria Liquefied Natural Gas Company that politicking and "bureaucratic bottlenecks" by multiple state agencies had hit operations.

The delegations were told "his administration will undertake appropriate reforms and implement fresh policies to boost national income from oil and gas production", according to his office.

It would also improve security to increase investment in the sector, as oil theft, maritime piracy and pipeline vandalism had exacerbated the global fall in the price of crude.