The grounded boxship Kea Trader has broken in two on a reef off New Caledonia.

Owner Lomar Shipping told TradeWinds four months of "continual pounding in sometime storm-force seas and the stress of sitting hard aground a flat rock reef" resulted in the 2,194-teu vessel (built 2017) fracturing vertically over the weekend.

"Noticeable vertical buckling in the mid-section of the hull side expanded during violent six-metre waves, causing the vessel to rupture completely into two halves on Sunday," it added.