March 6 (Reuters) - Argentina's national oil company YPF

swung to a net loss of $1.86 billion in the fourth

quarter, the firm said on Wednesday, driven largely by weaker

sales and a hefty impairment charge.

Revenues fell 9.7% to $4.194 billion from $4.645 billion in

the October-to-December period in 2022, it said in a statement,

despite the steady production increase from western Argentina's

massive Vaca Muerta shale formation, one of the biggest in the

world.

YPF said total oil and gas production increased 2% in

the fourth quarter, with crude output up 10%.

The company, one of Argentina's top domestic sellers of

refined fuels, said it took a $1.782 billion impairment charge

to pay for the deterioration of assets.

Operating costs in the quarter fell 4.1% year-on-year,

while earnings before interest, taxes, depreciation and

amortization (EBITDA), or core earnings, slid 5.9% to $1.151

billion.

The company reported weaker sales at gas stations in the

quarter, which were compensated partly by higher prices.

Argentina's new libertarian President Javier Milei

announced an energy sector "emergency" in mid-December shortly

after taking office, saying his government would tighten control

over the country's local gas and electricity regulators and seek

to allow long-controlled prices to rise.

The Argentine government holds 51% of YPF shares. As a

candidate, Milei said he

would seek to privatize

the firm once it gained value, in an effort to reduce the

state's share in the market and improve public accounts.

Milei's government has since backtracked from pushing

for privatization, removing the plan from a proposed package of

reforms.