MALBORK, Poland (Reuters) - Wielding swords and halberds, knights in heavy armor attack each other in scenes that could easily be mistaken for a staged reconstruction. But on the grounds of this vast brick castle in northern Poland, the battles are real.

Men and women from 25 countries gathered in their hundreds at Malbork Castle this weekend for the yearly full contact Medieval Combat World Championships in fast-paced fighting, reminiscent of the battles of medieval Europe.

Though less bloody than tournaments centuries ago, the battles are refereed matches, scored like boxing, in which the objective is to get one's opponent to the ground.

As well as one-on-one fights, there are bigger tournaments with groups of three, five or as many as 16 people on each side.

The fighters use swords, shields and polearms as they try to floor the opposition, cheered on by spectators.

"I like physical sports," says Andrey, a U.S. Marine Corps officer. "I like the tactics, I like the strategy, and I love leading men and women in battle."

Preparations can be a long, hard and expensive slog. Participants train several times a week, the equipment must follow strict authenticity rules and is checked for safety.

For the women competitors, the main event is a three-on-three tournament.

"We had to run a lot because fighters from other countries were heavier than us," Maya, the captain of the Polish women's team, says.

The four-day event at Malbork, the biggest brick castle in the world, saw the Poles scoop up most of the prizes. The U.S. team had dominated last year's championships in Spain.

"This year the Polish have come back really really strong," says Bill, an American. "There were just solid. It was a hard fight."

(Reporting by Reuters Television; Writing by Marie-Louise Gumuchian in London; Editing by Louise Ireland)