PAL Airlines has launched an appeal at the Chilean supreme court as it continues to battle the proposed merger of larger rival LAN Airlines and Brazilian carrier TAM.
Santiago-based PAL cast fresh uncertainty over the proposed deal, appealing against antitrust approval from regulator in Chile.
LAN gained approval for the merger, albeit with conditions, in September.
When complete the deal will create one of the largest airlines in the world, dominating the South American market.
Supreme court judges in South America must now decide whether to accept the objection.
This could take up to two weeks.
If it does hear the appeal, it could then take up to four or five months to issue a ruling.
However, LAN and TAM will be permitted to proceed with their tie-up in the meantime.
“Our company will study all the legal avenues to avoid a merger that does not abide by the basic principles of fair and healthy competition,” PAL Airlines said in a statement.