Taiwan had to use a mainland Chinese shipper to get vital materials to a $100 million port it is building on a disputed island in the South China Sea last month after it couldn't find a local firm to do the job, Taiwanese officials said Friday.

A coast guard official said the vessel from Shanghai Zhenhua Heavy Industry, a state-run company, was escorted by a Taiwanese patrol boat to Itu Aba Island on what he called an unprecedented mission.

Two other Taiwanese vessels monitored the ship while it unloaded its cargo of large caissons, or watertight chambers used in the construction of piers.