STX Offshore & Shipbuilding is said to have signed a letter of intent with Teekay Tankers for firm four 113,000-dwt tankers with additional options.
According to brokers, the contract have three additional options each consisting of a further quartet, and newbuilding price is reported to be around $43.5m each.
If total options for additional 12 vessels are exercised, total cost Teekay should pay leads up to about $700m.
These LR2 tanker quartet will be delivered from the end of 2015 to 2016.
Industry sources said the newbuildings would be built to Teekay's 'One Spirit' eco-design, which Teekay described as a vessel with a longer, slimmer hull form, reducing fuel consumption by 30%. Furthermore, One Spirit improves fuel efficiency by installing larger and slower propeller as well as G-type engine.