From Pacific Rim to Transformers, sci-fi fans have long had a love affair with the spectacle of gigantic robots locked in battle - and that dream is closer than ever to reality after an American company issued a challenge to a Japanese rival.

MegaBots Inc has offered to match their piloted "battlesuit" MegaBot Mk II against Suidobashi Heavey Industries' Kuratas mech in a battle royale that would be the first of its kind in the world.

In a video challenge on YouTube, the MegaBots team boast they have "America's first fully-functional, giant, piloted robot".

And in a salute to their own American patriotism, they have added one new feature - "really big guns".

The gun itself is just designed to shoot paintballs - but a paintball from a 4.5m-tall robot is still sure to pack a wallop.

The MegaBot Mk II is designed to shoot 1.3kg paint "cannonballs" at speeds of 160km/h.

The MegaBots team say the fight between their piloted battlesuit and the first-of-its-kind Kuratas is more than an inevitability - it's a duty.

"You have a giant robot, we have a giant robot - you know what has to happen," one of the flag-wearing MegaBot pilots says in the challenge.