The annual number of passengers using Tokyo's Haneda airport for domestic flights topped the 50 million mark Monday, 67 years after it opened in 1931, Haneda officials said.

The airport, Japan's main domestic hub, marked the occasion with a ceremony attended by officials from the Transport Ministry, terminal operator Japan Airport Terminal Co. and seven airlines with domestic flight operations at the airport.

In contrast to sluggish traffic at Narita and Kansai -- Japan's two international gateways -- Haneda has seen the number of passengers on domestic flights grow by as much as 40 percent over the past 10 years.

This year, competition also has stiffened at Haneda as two new operators -- Skymark Airlines and Air Do -- joined the domestic market, which had been controlled for 35 years by All Nippon Airways, Japan Airlines, Japan Air System and their affiliates.

Skymark launched regular service between Haneda and Fukuoka in September, and Air Do launched Haneda-Sapporo service earlier this month.

According to airport officials, Haneda is one of the busiest airports in the world in terms of domestic service.

The number of domestic passengers using Haneda this year was the fourth highest in the world, following Hartsfield International Airport in Atlanta, O'Hare International Airport in Chicago and Fort Worth International Airport in Dallas, the officials said.

Along with domestic service, Haneda also provides air links between Tokyo and Taiwan.