The government says airlines should disclose fees for checked baggage, carry-on items and other services to make it easier for travelers to discern the true cost of a ticket, the federal government said on Wednesday, according to the Associated Press.

The proposed Transportation Department disclosure rules, which build on regulations from 2009 and 2011, would stipulate that online flight search sites like Expedia, Google and Kayak provide more information, the AP reported.

Carriers would have to spell out specific charges for carry-on items and advance seat assignments, according to the AP.

Airlines for America, a Washington-based lobby for U.S. airlines, said the proposed rules could raise airline costs and result in higher airfares or reduced service, the AP reported.

"We believe this proposal overreaches and limits how free markets work and will have negative consequences," Airlines for America spokeswoman Jean Medina said in a statement, according to the AP.

A Southwest Airlines spokesman said the carrier has not had enough time to review the proposals, the AP reported. American Airlines and United Continental deferred to Airlines for America for comment.

The proposed consumer protections come as the airline industry supports legislation that would rollback rules requiring greater disclosure of fees and taxes for airfares, according to the AP.

The Transparent Airfares Act of 2014 would allow airlines to play up base fares in advertising, but disclose taxes and fees separately, the AP reported. The measure is backed by Airlines for America.

The move is "a direct pushback to what A4A (Airlines for America) is trying to do, which is to really make things more opaque," said Robert Mann, an airline consultant in Port Washington, New York, according to the AP.

"That's the way airlines used to advertise and the DOT banned it long ago," Mann said, the AP reported.

In recent years, airlines have implemented extra charges for items once included in the ticket price, according to the AP. More airlines have added these so-called ancillary fees, with low-cost carrier Frontier Airlines last month disclosing it planned new charges for carry-on bags and certain seats.

The Transportation Department said charges for additional air-travel services were difficult for buyers to determine up front, the AP reported.

The proposal would also require airlines and agents to disclose on website itinerary displays whether flights sold are operated with other carriers, according to the AP. Big travel agents would have to respond quickly to consumer complaints and offer the option of holding reservations at quoted fares without payment for 24 hours if made a week or more before departure.