A containership venture backed by billionaire Idan Ofer and the Lauro brothers of Monaco has doubled its investment in mega-boxships.

Quantum Scorpio Box has exercised options on three newbuildings at Samsung Heavy Industries (SHI) to take its spending to $900m, according to informed sources.

The move lifts its tally of 19,200-teu vessels at the South Korean yard to six, with the first set to enter service in mid-2016.