United Airlines drew a $2.7 million fine from the government on Thursday for violating rules aimed at protecting disabled passengers and preventing long tarmac delays.

The Transportation Department said there was a significant increase in 2014 in disability-related complaints regarding United. A department review found that United had failed to give passengers with disabilities prompt service getting on and off planes, and in many instances damaged or delayed the return of wheelchairs and other mobility devices.

The department cited United operations at Houston International Airport, Chicago O'Hare International Airport, Denver International Airport, Newark International Airport and Washington's Dulles International Airport.

United also was fined for five lengthy delays in which passengers were kept waiting in planes on the tarmac at O'Hare airport during severe winter weather on Dec. 8, 2013, and for another delay at Houston Hobby Airport on May 20, 2015.

In a statement, United said it remains committed to meeting all Transportation Department rules, particularly during difficult operating conditions.

The airline also said it was continuing to invest in cutting-edge technologies to improve its ramp processes and had launched automated aircraft parking systems at two of its largest hubs. The systems were enabling it to reduce taxi times and safely guide aircraft to the gate when conditions might have previously prevented it from accommodating passengers, United said.