Leading tonnage provider Seaspan Corp has firmed up an order for up to a dozen neo-panamax boxships.

The company said it has placed orders for four 12,000-teu and four 15,000-teu vessels, as well as options to build another four 15,000-teu vessels.

The vessels have been ordered “on the back of long-term charters “with a long-standing major liner customer”, the shipowner said.