Sun Country Airlines has told its employees to prepare for a possible shutdown, though company leaders said they believe they will be able to keep the low-cost carrier aloft.

The Mendota Heights-based airline, a favorite of leisure travelers on a budget, has seen its future clouded by problems at its parent company at a time when airlines already are struggling because of high fuel prices and a weak economy.

In a notice to employees Wednesday, Sun Country said, "there are obviously risks that no solution will be found (to the company's financial troubles). This is to notify you that should Sun Country not be able to obtain additional financing or obtain relief from our major creditors in the near future there is a distinct possibility that the airline will be shut down and/or you will be furloughed."

The letter tells employees to prepare for that possibility as early as Dec. 1.

The upheaval at Sun Country is tied to an ongoing federal investigation at the airline's parent company, Minnetonka-based Petters Group Worldwide. A former Petters employee was charged this week with mail fraud and money laundering in a scheme that allegedly helped the company raise billions of dollars over more than a decade. Tom Petters, Petters Group Worldwide's founder and CEO, resigned Monday.

Sun Country Airlines, which Petters bought with other investors in 2006, has not been implicated in the investigation.

Sun Country currently has 850 employees, 1,100 in peak season.

This week, Sun Country CEO Stan Gadek said that during these current slow months for the airline, it would typically rely on Petters for a short-term loan. That would carry it until early 2009, when Sun Country's business would pick up with winter getaway travelers.