DENVER -- Frontier Airlines began charging travelers $25 for a second checked bag.

The new charge took effect Tuesday. Frontier announced the move last month as part of its efforts to cover rising fuel costs.

Customers who bought tickets on or after Tuesday had to pay the charge. People who bought their tickets earlier were not charged for a second checked bag.

Frontier also raised prices for oversized and overweight bags from $50 to $75 as well as the fee for paper tickets from $25 to $35.

In addition to raising prices, Denver-based Frontier reduced aircraft fuel burn and began using new flight planning computer software to track fuel and flights to save fuel.