Aeromexico airlines filed for bankruptcy because a strike by 7,500 groundworkers is costing the state-owned company more than $1 million a day, a spokeswoman for the Transportation Ministry said Saturday.

Spokeswoman Norma Herrera said Aeromexcio filed bankruptcy papers Friday night after four days of an ongoing strike stranded thousands of people in Mexican cities and forced many international travelers to seek alternate routes.

About 7,500 members of Aeromexico's National Union of Technicians and Workers went on strike Tuesday to protest the proposed sale of 13 of the company's planes, saying the sale would cause the loss of up to 3,500 jobs.