Newly appointed United Airlines CEO Oscar Muñoz is believed to remain hospitalized after suffering a heart attack late last week.

According to the Wall Street Journal, the 56-year-old Muñoz was admitted to a Chicago hospital on Friday. Since taking over as the face of the nation's No. 2 airliner by capacity, he had pledged to work nonstop in fixing the company's operational problems and in mending fences with the company's 85,000 workers who have been at odds with management ever since a 2010 merger with Continental resulted in the creation of United Continental Holdings Inc.

In a brief statement released on Friday, company officials stated they had been "informed by Oscar's family that he was admitted to the hospital on Thursday and we will provide further details as appropriate. In the meantime, we are continuing to operate normally."

On the day the married father of four fell ill, he was scheduled to host a summit with labor leaders working on hammering out new contract agreements with the company's pilots and mechanics. In addition, he was also slated to host his first quarterly earnings call with shareholders later this month. United shares closed down 3.1 percent at $55.97 on Friday.

Company officials are said to be closely monitoring Muñoz's condition in hopes of quickly determining if the airliner will need to install an interim leader during his absence.

"It could be a mild heart attack, and he could be back in two weeks," said a source.

In recent months, United has also been dogged by a federal corruption probe focusing on the company's relationship with the Port Authority of New York and New Jersey.

Prior to coming on board with United, Muñoz served as president and CEO of Jacksonville, Florida-based transportation company CSX.