TOKYO - Japan's cabinet was expected Tuesday to send to parliament a bill allowing the coast guard to inspect North Korean ships for nuclear- and missile-related materials, in line with a UN resolution.

The bill would authorise the coast guard to inspect ships both on the high seas and in Japanese waters. Inspectors however would first be required to get approval from the captain of any ship targeted and from its country of origin.

North Korea has warned it will not tolerate inspection of its ships by Japan.

Japanese Prime Minister Taro Aso's cabinet hopes parliament will pass the bill by the end of this month, officials said.

However the bill's passage is not assured. The legislature's upper house is controlled by the opposition and the unpopular premier is expected to call elections as soon as next month and no later than September.

A UN Security Council resolution passed last month over North Korea's recent nuclear and missile tests calls on member states to stop and search vessels suspected of carrying banned weapons for the communist state.

Japan's Maritime Self-Defence Force, which is banned from offensive military action, could be called on to back up the coast guard if a ship targeted for inspection appears heavily armed, government officials said.

Neither the UN resolution nor the Japanese bill authorise the use of force.

North Korea, which often points to Japan's former harsh colonial rule over the Korean peninsula and accuses it of a militarist revival, has made clear its objections to inspection.

'Our ships are sacred and impregnable places where our sovereignty reigns,' North Korea's Rodong Sinmun daily said last week. 'If anyone hurts them, it would be considered a grave military provocation against us.'

Japan, along with the United States, pushed hard for tough sanctions after the North's long-range rocket launch on April 5 and after its second underground atomic test on May 25, which was followed by a series of missile launches.

Japan separately banned all exports to North Korea last month.