Sinokor Merchant Marine has doubled its tally of aframax tankers on order at K Shipbuilding to four.

Shipbuilding sources said the South Korean shipping company added two more 115,000-dwt newbuildings some time ago but the deal went unreported.

An executive at K Shipbuilding declined to disclose his company’s shipbuilding activities, citing contract confidentiality. Sinokor did not respond to requests for confirmation or comment.

Sinokor’s latest tanker newbuildings are options that it held at K Shipbuilding when it signed for its earlier two tankers last year.

The company is said to have paid more than $50m each for the vessels. K Shipbuilding is scheduled to deliver the quartet in February, May, September and December of 2023.

Brokers said Sinokor did not order the four aframax tankers on speculation. It has booked the crude carriers on the back of charter contracts of at least five years from oil major ExxonMobil.

Separately, Sinokor is also due to take delivery of two LNG-fuelled aframax tankers from Samsung Heavy Industries this year. The two newbuildings — to be named Pacific Coral and Pacific Topaz — were part of a 12-ship order that it inked at the Geoje shipyard in 2020 for charter requirements from Shell.

On the smaller tanker segment, Sinokor has six MR tankers worth $222m on order at K Shipbuilding. ExxonMobil was also said to be the charterer of the sextet.

The vessels, to be delivered next year, will be built to meet the International Maritime Organization’s Energy Efficiency Design Index Phase 3 compliance standards for greenhouse gas emissions, as well as existing Tier III NOx standards.

A low-profile shipping company, Sinokor has a diversified fleet that includes LNG carriers, VLCCs, large bulk carriers, container ships and tankers. The company has 169 vessels on the water, according to Clarksons’ Shipping Intelligence Network.

K Shipbuilding was formerly known as STX Offshore & Shipbuilding. It was renamed last year when merger-and-acquisition specialist KH Investment and debt clearing company United Asset Management took over the yard for KRW 250bn ($223.4m).

The new owner of K Shipbuilding has plans to transform it into a smart shipyard and build carbon-neutral ships.

KH Investment is continuing to invest in the shipbuilding industry. It is set to own a second shipyard. The financial company was selected as the preferred bidder by Korea Development Bank to take over aframax and suezmax tanker specialist Daehan Shipbuilding.

KH Investment was said to have offered $200m for the 90% stakes that the bank controls.