Oilfield service provider Schlumberger said that its primary customer in Mexico is late making payments on some $500 million as of the end of 2021, the company reported in a regulatory filing on Jan. 26.

Accumulated debt at the end of 2020 by the customer, whose name Schlumberger did not disclose, was $700 million, according to the filing.

Mexico's highly indebted state-run oil company Pemex has intermittently accumulated debt to providers in recent years, but the company has said it is capable of meeting its financial commitments.

Pemex did not immediately respond to a request for comment.

Schlumberger said receivables from the customer are not in dispute, and that it has not historically faced any material write-offs due to uncollectible accounts receivables from the customer.

Pemex, whose financial debt was $113 billion at the end of the third quarter, in December said it will conduct "a liability management transaction" of outstanding securities this year, funded with a capital injection of up to $3.5 billion from the government.