TOKYO - Japan's parliament has unanimously adopted a call for a nuclear weapons-free world in a resolution passed by both chambers that cleared the upper house Wednesday.

The resolution, which refers to US President Barack Obama's call in April for a world without atomic weapons, and to North Korea's May 25 underground nuclear test, was submitted by a bipartisan group of legislators.

"Japan, as the only nation to have been attacked with atomic bombs, has a responsibility to spearhead efforts to eliminate nuclear weapons around the world," the resolution says.

"The government needs to make efforts toward eliminating nuclear weapons, by trying to extend the regional efforts over the issue of North Korea's nuclear programme to the global level."

The bill urges the government to work harder to establish an effective international inspection system to prevent the proliferation of nuclear weapons and related technologies or materials.

Japan's Hiroshima and Nagasaki cities were obliterated by US atomic bombings in August 1945. More than 200,000 people were killed, either instantly or in the days and weeks that followed. Japan surrendered several days later.

Japan, has been officially pacifist since World War II, but Pyongyang's latest nuclear test has reignited a sensitive debate among conservative politicians about strengthening Japan's military, including allowing it to launch pre-emptive strikes if a missile attack is imminent.