The company, which is part of the A.P. Moller-Maersk conglomerate, said it has utilized an option to order two new build MR vessels from South Korean shipyard Sungdong Shipbuilding & Marine Engineering.
"In November last year, Maersk Tankers ordered four MR vessels with an option of further two vessels. This option has now been utilized," the company said.
Maersk Tankers, which did not indicate the cost of the MR tankers, said the expected delivery of all six vessels was over 2016-2017.
The Copenhagen-headquartered company said the investment aligned with its continued strategy to focus on the oil product segments.
An MR tanker can transport about 30,000-40,000 mt of oil products. An MR vessel is also able to carry about 35,000 mt of crude.
"We believe that the product segments have a reasonable chance of returning to attractive rates in the coming years and in order to stay relevant and attractive in these markets, we need to gradually renew our fleet to maintain a suitable average age," CEO Morten Engelstoft said in a statement.
Maersk Tankers operates in the crude and oil product segments and manages a fleet of more than 150 vessels.
In November, when it announced the order for four MR ships, then-CEO Hanne Sorensen said her company`s MR fleet was its oldest, which was why the company was beginning the renewal there.
Maersk has also said previously that it is renewing its MR fleet, but not expanding it.
The company has been rebalancing its fleet portfolio to focus on what it sees as the more healthy side of the business.
Last month, new CEO Morten Engelstoft said the company had sold its fleet of 15 VLCCs to Antwerp, Belgium-based Euronav NV for $980 million.
Engelstoft told Platts in a telephone interview that he saw more years of pain ahead for crude tankers, while the product tanker sector would probably be the first to recover.