Tokyo  - Japan may extend economic sanctions against North Korea past their April 13 deadline if Pyongyang goes ahead with a planned rocket launch, a top government spokesman said Thursday.

Japan "aims to reinforce its stance in seeking progress in dialogue [with North Korea]" by extending sanctions for another year, Chief Cabinet Secretary Takeo Kawamura said at a press conference.

The Stalinist state has been preparing to launch a communications satellite between April 4 - 8, which is widely believed to be a cover for a long-range ballistic missile test.

After North Korea test-fired ballistic missiles in July 2006 and conducted a nuclear test in October the same year, Japan stopped runs of the Mangyongbong-92 ferry connecting the two countries and banned imports.

The Japanese government is considering a ban on exports and restricting goods to be carried by those who enter North Korea amid reports saying Pyongyang began fueling the rocket as the announced launch window draws nearer.

Japan has set up Patriot-guided missile fire units for air defence at five locations, including the capital Tokyo, while it deployed two Aegis destroyers with interceptors in the Sea of Japan.

Its Defence Ministry gave orders to shoot down any missile debris in case the launch failed and the parts were to hit Japanese territory. (dpa)