Avianca said it is analyzing offers to form a strategic partnership but added it is not under an obligation to close any arrangement.

The Colombian airline did not disclose which airlines had made the offers. US carriers Delta Air Lines and United Airlines and Panama’s Copa Airlines have expressed interest in partnering with Avianca.

The airline said it will decide what steps to take after it reviews the terms and conditions of the proposals with its advisors. Avianca’s controlling shareholder, Synergy Group, has hired Bank of America Merrill Lynch to advise it on a possible partnership.

According to an M&A source familiar with the process, Synergy could receive a cash and stock offer for roughly $500m if it decides to sell a controlling stake in Avianca.

Avianca requested approval this week to operate local and international flights in Argentina. The Argentine government will hold a hearing on December 27 to consider the proposal. The Colombian airline already operates subsidiaries in Ecuador, Guatemala, Honduras, Peru and El Salvador.