South Korea's Dae Sun Shipbuilding & Engineering has added four feeder container ship newbuildings worth nearly $88m to its orderbook.

The midsize shipbuilder said two companies each ordered a pair of gearless 1,000-teu ships.

It declined to disclose the names of the buyers, citing contract confidentiality.

However, shipbuilding sources familiar with the deals said Greece's Cosmoship Management and domestic liner company Namsung Shipping have signed the contracts, which do not include any options.

The companies were said to have paid close to $22m apiece for the ships. They are both scheduled to take one in 2023 and the other in 2024.

Sources said Namsung has ordered the vessels for its subsidiary Dong Young Shipping, a feeder operator specialising in "north-bound shipments" between South Korea and Russia.

Namsung is also due to take delivery of a similar-sized container ship from Dae Sun next month. The vessel was part of a two-ship order that it made two years ago for a reported price of between $17m and $18m each.

It took delivery of the first vessel, the Star Chaser (built 2021), last month. It is deployed on a trade loop linking South Korea, China and Japan.

Namsung also has three boxship newbuildings under construction at Hyundai Mipo Dockyard (HMD) that it ordered last year.

The shortsea liner company was reported to have paid close to $41m each for two 2,500-teu boxships for delivery next year and close to $30m for one 1,600-teu vessel due for delivery in November this year.

Cosmoship's deal at Dae Sun lifts its orderbook to six ships.

It has four 1,500-teu newbuildings under construction at Huangpu Wenchong Shipbuilding in China. The quartet was ordered last year at between $22m and $23m per each. The vessels will meet International Maritime Organization Tier III emissions rules and Energy Efficiency Design Index phase 3 standards and are slated for delivery in 2023.

Dae Sun, established in 1945, is one of the few medium-size shipyards left in South Korea. Domestic steel manufacturer Dongil Steel became the major shareholder early last year when it paid KRW 165bn ($138m) to state-owned Export-Import Bank of Korea for 83% of the yard's shares.