Tokyo:
A huge World War II bomb uncovered near a busy runway was underneath a shield of concrete and sandbags on Wednesday as flights resumed at an airport in northern Japan, a government official said.
A worker rebuilding drainage systems at Sendai Airport -- which was swamped by last year's tsunami -- on Monday uncovered the 500-pound (225-kilogramme) bomb, believed to have been dropped by US forces.
Bomb disposal experts ordered the construction of three-metre-high (10-foot-high) concrete walls, supported by soil up to the same height, to protect the bomb.
Crews piled some 300 sandbags, each weighing a tonne, on top of the mound to construct a casing that stands six metres high.
The 110 centimetres (43 inches) long bomb is now sitting at the bottom of the structure, waiting for military experts to defuse and remove it once legal and logistical details are worked out, the transport ministry official said.
"The work to defuse it will start after we discuss the matter with local municipalities and residents," he said.
Troops believe the bomb is unlikely to explode unless unusually strong force is applied, according to local media.
The airport resumed operations, using one of its two runways, after having cancelled all 92 domestic and international flights on Tuesday.
"We are using our main 3,000-metre runway. So far we are not experiencing any delay to our flight schedule," the land ministry official said around midday.
Nearly 70 years after the war ended, unexploded bombs and shells are still occasionally found in Japan, particularly on the southern island of Okinawa, the site of an extremely bloody battle towards the end of World War II.
Less than two weeks ago, Japanese troops defused a similar 500-pound WWII bomb found in a busy business district of Tokyo.
Sendai Airport was devastated in the quake-triggered tsunami that hit Japan in March 2011. Footage posted on YouTube of waves covering the runway has been seen by more than 20 million people.