Under the contract signed Monday, China's Shanghai Waigaoqiao Shipbuilding Co. will build at least four 186,300-tonne bulk carriers for U-Ming Marine, with delivery scheduled for 2014, the Taiwanese firm said in a statement. U-Ming, which is owned by Far Eastern Group, one of Taiwan's biggest conglomerates, also has an option to buy six more vessels of the same type, according to the contract, which is worth up to $500 million, it said. U-Ming said modest expectations for the shipping industry in 2012 had allowed it to buy the vessels at "very competitive prices". China claims sovereignty over Taiwan, but the island has ruled itself for more than six decades since a split in 1949 at the end of a civil war. Ties between the two former bitter rivals have improved after Ma Ying-jeou of the China-friendly Kuomintang party came to power in 2008.