Sydney Airport says plans by Qantas to code-share with Garuda Indonesia could drive up costs for consumers by worsening Australia’s case to increase its air rights into Bali and promote more competition from Virgin Australia.

In a submission to the International Air Services Commission, Sydney Airport head of corporate affairs Karen Halbert said Australian airlines only had 91 surplus seats under the existing bilateral agreement, while Indonesian and foreign carriers could still add another 12,285 seats.