Washington: The US Defence Department said bad weather in the north Pacific makes it unlikely that a Navy ship will launch a missile in an attempt to shoot down a wayward US spy satellite in space.

A department official who briefed reporters on technical aspects of the decision on when to make the shootdown attempt said high seas currently are an obstacle for the Navy ship that would fire the missile.

But the official also said no decision has been made yet to scrap the mission, and if the weather improves during the course of the day the launch could go forward. The intercept is estimated to cost between $40 million and $60 million.

Armed with two specially modified interceptor missiles, the USS Lake Erie has been tasked to intercept the satellite over the Pacific and shoot it down into the ocean, officials said, adding that a cruiser was already in waters off Hawaii.

A guided missile destroyer was carrying a third missile in case the first two attempts fail.