Major air carriers raising airfares

New York (KTVU and wires) -- You should expect airfares to start going up the next time you fly.

Reuters news agency reports that three major airlines are increasing airfares.

Reuters cites travel search website, FareCompare, that Delta raised fees by up to $4 one-way, starting Monday.

Southwest Airlines was next to raise ticket prices by $3 one-way, followed by American Airlines, which also increased domestic fares by $3 one-way.

Reuters reports that this move comes, as the U.S. Justice Department is investigating whether air carriers have worked together to illegally keep fares high, by indicating intentions to limit the number of flights that will be available.

The various airlines could not be reached for comment.