The 1,000-member Cabin Crew Union of LAN Express, which had negotiated for more than two months with the airline, the region's largest carrier, said in a statement it would explain its reasons in a news conference later on Thursday.
LATAM, meanwhile, said the protest could not officially end until the termination of the strike was approved by authorities. "Unfortunately, the way in which the union would have ended the strike does not comply with the law," the company said.
Shares of LATAM Airlines were up 1.77 percent at 9,433 pesos on the Santiago Stock Exchange in early morning trade.
LATAM was created in 2012 through a merger of Chile's LAN and Brazil's TAM. The company, headquartered in Santiago, has operating units in Argentina, Brazil, Chile, Colombia, Ecuador, Paraguay and Peru.