United Airlines has put through changes to its frequent flier award chart, increasing the number of miles that fliers need to receive some of the most popular rewards, according to USA Today. The carrier confirmed the changes in policy to Today In the Sky on Friday.

"We're increasing miles required in these markets for the first time in several years to account for the increased cost of providing transportation, particularly in the premium cabin and particularly on the Mileage Plus partner carriers," Rahsaan Johnson, a spokesman for United Airlines, told Today In the Sky. "We faced a decision other airlines have faced - to either increase the number of miles required for partner awards or to eliminate them altogether."

Johnson said that the airline would "prefer to keep those options at an increased cost instead of eliminating them."

The changes went into effect just after midnight eastern time on Friday morning, when a representative for United posted an alert on the message boards at FlyerTalk.com and Milepoint.com, sites for frequent-fliers to discuss travel.

The post said that they were notifying travelers "about some changes we'll be making to our MileagePlus award chart and upgrade policies."

The number of miles needed will change for both the "Saver" and "Standard" level of frequent-flier tickets, which will also include the number of miles needed for domestic "stopovers." The changes will also affect travelers on first-class and business-class tickets on Star Alliance partners, including Lufthansa, All Nippon, Thai Airways, Air Canada and many others.

According to United Airlines, the changes will take effect for all tickets issued on or after February 1, 2014.

MilesCards.com is a credit card website that is geared to frequent travelers, and they have compiled a table to summarize the airline's changes to help make it easier for travelers to see exactly what they are.

Some of the biggest increases are hitting United partner airlines. As expected, reaction from frequent fliers was negative.

The changes are "really nasty" Gary Leff, a frequent flier expert, wrote on his blog "View from the Wing," adding that "the biggest bloodbath is to first class partner award pricing."