(LEAD) S. Korea bans sales, nullifies certifications of Volkswagen vehicles

(ATTN: ADDS more info in paras 4-6, 7-8; minor edits)

SEOUL, Aug. 2 (Yonhap) -- South Korea's government on Tuesday banned sales and revoked the certifications of 80 vehicle models of Audi Volkswagen Korea, which has been suspected of obtaining permis