TS Lines' appetite for newbuildings shows no sign of being satiated.

With the ink hardly dry on a deal at Shanghai Waigaoqiao Shipbuilding (SWS), the Taiwanese liner company has signed a newbuilding contract with Fujian Mawei Shipbuilding to build two more 2,900-teu container ships.

The latest contract at Mawei brings the total number of 2,900-teu newbuildings that TS Lines has booked at the shipyard to six.

The company's earlier four newbuildings were ordered in November and all, including the latest pair, are slated for delivery between 2023 and 2024.

A Mawei official confirmed TS Lines' order, adding that the two vessels were a new contract and not option vessels.

The price of the 2,900-teu newbuildings was not disclosed but brokers estimate they would cost in excess of $40m each.

The container ships will be built to comply with the International Maritime Organization's Energy Efficiency Design Index (EEDI) Phase 3 for greenhouse gas emissions and Tier III NOx standards.

A shipping source familiar with TS Lines said the company is in the "fleet-expansion mode", with the aim to reduce its chartering expenses being one of the reasons for building up its owned fleet.

Earlier, the company ordered two 7,000-teu boxships at SWS for delivery in 2024, bringing the order tally of midsize container ships that it has at the Shanghai-based shipyard to six.

These conventionally-fuelled vessels were said to cost around $73m apiece and are slated for delivery between the end of 2023 and 2024.

The deals at SWS and Mawei take TS Lines' total orderbook to 26 ships worth around $1bn.

According to IHS Markit, TS Lines has five 1,900-teu and one 2,693-teu newbuildings under construction at Guangzhou Hyuangpu Wenchong Shipyard for delivery between now and 2023. Mawei is also constructing eight 1,100-teu vessels for the company for delivery in 2023 and 2024.

According to Alphaliner, TS Lines operates 50 container ships, of which 25 are owned. It is the world's 20th largest liner company.

TS Lines is planning to launch an initial public offering in Hong Kong. Funds raised could be used to finance the expansion of its fleet.