South Korea's polyester fibre exports plunged 17.1 per cent in the first half of 2002 to $1.1 billion amid fierce competition from rival nations such as China, the Korea Textile Trade Association revealed on Thursday. The association said exports to its five major export markets slumped nearly 20 per cent, with exports to Mexico and Argentina the worst hit with exports down 40.6 per cent and 91.7 per cent, respectively.