MOSCOW (Reuters) - Russian petrochemical holding Sibur said on Monday it had no direct dealings with U.S. Commerce Secretary Wilbur Ross and that its ties to its partners were not in breach of sanctions imposed on Russia over the Ukraine crisis. Sibur was commenting on reports that Ross has kept investments in Navigator Holdings, a shipping firm which has supplied services to Sibur. Stakeholders in Sibur include an associate of Russian Vladimir Putin who is subject to U.S. sanctions. In a statement, Sibur said that in the first half of this year, Sibur spent $15.9 million on services provided by Navigator, or 2.8 percent of Sibur’s overall expenditure on logistics. It said Navigator was never a sole contractor for shipping Sibur’s petrochemical products. “All negotiations and meetings were held solely by Sibur management and solely with management of those companies (which were shipping Sibur’s liquefied petroleum gas) and without shareholders’ involvement,” Sibur said in an emailed statement. “In connection with the introduction in 2014 of sanctions with regard to one of the company’s shareholders, our counter-parties conducted all necessary checks into whether there were any restrictions on working with Sibur. No such restrictions were found,” the statement said. “Sibur expresses its surprise at the politically-charged interpretation in certain media publications of regular commercial activities, over many years, which from the outset were reflected in the company’s published accounts.” Sibur’s shareholders include Gennady Timchenko, a close Putin ally who has been under U.S. sanctions since 2014. Another Sibur shareholder is Putin’s son-in-law, Kirill Shamalov. Shamalov did not reply to an email from Reuters seeking  comment. Spokesman for Volga Group, an investment vehicle for Timchenko’s assets, declined to comment.  The New York Times and other publications, citing leaked documents from an offshore law firm, reported that partnerships used by Ross have a 31 percent stake in Navigator Holdings. Reuters has not independently verified the documents. 