U.S. authorities have stopped an oil tanker traveling from Russia to New Orleans to check whether the product it was carrying was Russian in origin, a source confirmed to Reuters, and a spokesperson for the company that chartered it said it was not.

The Vitol-chartered vessel was shipping intermediate oil products including vacuum gasoil and fuel oil from Russia’s Taman port to New Orleans last week, according to a trading source and shipping data.

The U.S. imposed sanctions on Russian oil products following its invasion of neighbor Ukraine in late February.

“I can confirm on the record that this cargo is not Russian origin,” a spokesperson from Vitol told Reuters.

The products were due to reach a Valero refinery in the New Orleans region, two sources said.

The cargo was stopped by U.S. Customs and Border Protection (CBP) to confirm the product on board was not Russian in origin, according to a source familiar with the matter, adding that the shipment is of Kazakh oil products.

CBP and the Department of Homeland Security did not immediately respond to requests for comment. The Coast Guard said it had no comment.

The story was first reported by the Wall Street Journal.

The U.S. sanctions do not include Kazakh oil products, which travel on Russian pipelines.

Vitol said it is complying with sanctions and will not enter into any new Russian crude and product transactions and has ceased trading Russian origin crude oil and product, unless directed otherwise.