The first shipment of U.S. crude oil is heading to Belarus this week, fulfilling a commitment made in February, U.S. Secretary of State Mike Pompeo said.

The shipment involves by U.S. firm United Energy Trading, with the assistance of U.S. firm Getka and Polish partner UNIMOT.

"This competitive deal ... strengthens Belarusian sovereignty and independence, demonstrates that the United States is ready to deliver trade opportunities for American companies interested in entering the Belarusian market," Pompeo said.

Belarus, a close ally of Russia, became involved in a row with Moscow earlier this year over the price it pays for Russian oil. The dispute has since been concluded, but Belarus has said it wants to diversify its oil imports.

In late April, Belarus, which has long relied on Russian oil, purchased its first crude from Saudi Arabia, according to state refiner Belneftekhim.

"The United States urges Belarus to build on the progress it has made to increase the access of American businesses to its market and undertake the market-oriented, trade-liberalizing reforms necessary to advance its WTO (World Trade Organization) accession process," Pompeo said in a statement.