John Fredriksen has moved swiftly to increase his stake in rival tanker company Euronav, latest US regulatory filings show.

He now controls 19.8m shares, or 9.8% of the US-listed Belgian tanker owner, according to a filing with the US Securities and Exchange Commission.

This makes him the company's biggest shareholder, beating the 8.3% in treasury stock owned by Euronav itself.