SPP Shipbuilding has reportedly won an order for up to 12 MR tankers.
Mexican oil company Pemex is said to have splashed out more than $400m on the newbuildings.
Industry players say the state-owned oil company has booked up to 12 medium-range (MR) tankers at the South Korean shipbuilder for delivery in 2013 and 2014.
The deal is said to be for six firm vessels plus six options at around $34m each.
Shipbuilding players familiar with the deal say it was agreed in August and has only just come to light.