OAKLAND — As the summer travel season kicks off, Oakland International Airport is seeing major passenger growth.

The airport reported its busiest month of May in eight years, with more than 1 million travelers through the airport that month. That is an increase of 5.8 percent, or 54,591 passengers, over last May and marks the 30th consecutive month of year-over-year growth at the airport.

“We are very pleased to witness this continued upward pattern as the busy summer travel season gets underway,” said airport director Bryant Francis in a statement from the airport. “There is a growing awareness of (the airport) as a major air access channel, not just for the East Bay but for the entire Bay Area. This is echoed by our air carrier partners through the addition of flights and new nonstop routes, and from our customers through making ever greater use of the steadily increasing number of available seats.”

The reported growth follows the launch of the first direct service to London from Oakland on Norwegian Air, which has in the past two years also launched service to Oslo, Norway, and Stockholm.

The Oakland airport has more than doubled its direct domestic routes since 2006, with more stops on the horizon. Passenger traffic growth is likely to increase again in June, the airport said.

Southwest Airlines launched new daily flights earlier this month from Oakland to Long Beach, Reno-Tahoe and St. Louis, adding over 1,000 daily outbound seats.

While total passenger volume at Oakland remains far below that of San Francisco International, it is on the upswing again after a sharp decline during the global economic recession and is expected to approach its all-time high by 2020.

The airport is working on a $35 million expansion to its international arrivals building that will double its international flight capacity. There is also the ongoing $200 million renovation of Terminal 1, which was started in 2008 to update and modernize the airport.

Contact Annie Sciacca at 925-943-8073. Follow her at Twitter.com/AnnieSciacca.