Orbital Sciences postponed its planned launch of the Cygnus cargo ship toward the International Space Station on Monday due to a boat in the waters near the Virginia launch pad.

"Tonight's launch of the Antares rocket carrying the Cygnus cargo craft has been scrubbed," a NASA commentator said on the US space agency's live broadcast.

The boat was located inside the rocket's designated safety range, just to the southeast, and Orbital decided it was too risky to send the rocket soaring overhead.

Attempts to contact the boat were unsuccessful, NASA said, and the liftoff had to be scrubbed 10 minutes before it was scheduled to go.

"Tonight's Antares launch has been postponed because of a ship in the mariner avoidance area," Orbital said on its launch blog.

The next launch attempt is expected Tuesday at 6:19 pm (2219 GMT).

The cargo ship is aiming to make its third contracted mission with NASA, carrying nearly 5,000 pounds (2,200 kilograms) of supplies and science experiments for the six orbiting astronauts.