The Turkmen Foreign Ministry said that Turkmenistan has limited natural gas supplies to Iran starting January over unpaid past deliveries, Reuters reported.

Ashgabat, which exports to Iran about 9bcm/y of gas, made the move after trying unsuccessfully to collect debts from the National Iranian Gas Company (NIGC) since 2013. Iran owed about nearly $2b, as the payments date back more than 10 years. Iran, for its part, sought arbitration, according to Eastern Daily News.

However, NIGC declared in a statement: “Cutting the gas flow is an obvious violation of the deal. Under the agreement, the Turkmen side cannot halt the gas flow even if there is debt or a payment delay. The company added that Iran had already paid “over $4.5b” to Turkmenistan, and that: “Most of this debt dated back more than a decade to when Iran was sanctioned and could not transfer cash, but even then, based on mutual understanding, NIGC exported parts and provided services to the Turkmen side in exchange.”

This came as Iranian Oil Minister, Bijan Namdar Zanganeh, said late december that Turkmenistan agreed to continue its gas exports temporarily. Although Iran possesses its own natural gas resources, the country imported gas from Turkmenistan for 20 years for its northern part of the country to use, especially during the winter.