LISBON, Dec. 1 (Xinhua) -- As of Monday, airport tax at Lisbon and Porto have increased by 7.56 percent and 1.5 percent, respectively, airport management company Aeroportos de Portugal(ANA) said on its website.

"The total increases over the last five years are the equivalent of less than a euro (97 cents)(about 1.2 U.S. dollar) per passenger and Lisbon airport's taxes are below the average for similar airports, such as Madrid," ANA said.

This is the fourth airport tax hike since the company was privatized at the beginning of 2013. Another airport tax increase is expected to be implemented on Jan. 1, 2015, according to the ANA, which is owned by French group Vinci.

The latest tax increase was announced in August. ANA said it was due to a higher-than-expected increase in air traffic. The International Air Transport Association projected this trend would continue in the second half of 2014.

Passenger traffic at Lisbon airport and Porto airport in November increased by 13.6 percent and 8.5 percent, respectively, ANA figures show.