Mexico's state oil company Pemex on Thursday reported losses of 346 billion pesos ($18.3 billion) for 2019, a 92 percent increase on last year's deficit.

Pemex said the results were due to the burden of $105 billion in debt, a drop in crude sales and an increase in tax payments.

The loss included almost 170 billion pesos in the fourth quarter of 2019.

Total sales dropped 16 percent in 2019 compared to the previous year, with the fourth quarter registering a 22 percent fall.

The government of Mexican  President Andres Manuel Lopez Obrador has invested $10 billion in Pemex in a bid to prop up the company's finances
The government of Mexican President Andres Manuel Lopez Obrador has invested $10 billion in Pemex in a bid to prop up the company's finances AFP / Ulises Ruiz

"The most important variables that explain this situation are the fall in the price of the Mexican (crude) mix for export; lower reference prices for petrol and diesel; and the reduction in the volume of sales both nationally and for export," Pemex said in a statement.

Pemex said its debt fell 4.8 percent compared to 2018 "mostly because of the early repayment of debt that formed part of the debt management operation of September 2019."

The company needs an investment boost to reverse a trend in reduced production, currently at 1.6 million barrels a day, down from 3.4 million barrels a day in 2004.

The left-wing government of President Andres Manuel Lopez Obrador has already invested $10 billion in Pemex in a bid to prop up the finances of a company considered a bulwark of national sovereignty.

The company's problems were exacerbated in mid-2019 when ratings agency Fitch downgraded Pemex's shares into a speculative category due to their high risk.