TWO Royal Navy teams will fight it out in Glasgow's George Square in one of the world's toughest sporting challenges.

Large crowds are expected to watch the gruelling field gun challenge, which will take place on Monday.

The event, regularly televised from the Royal Tournament in London and at the Military Tattoo at Edinburgh Castle, involves two 18 strong crews from Navy bases at Faslane and Rosyth.

They will race against each other, and the clock, to decide the winner.

Three times in three hours they will dismantle a one-tonne gun, run at breakneck speed while carrying the gun to the other end of the square, and reassemble and fire the weapon. They then repeat the exercise and race back to where they started.

It is not unknown for team members to break bones or even lose a finger while taking part in the dangerous challenge.

This year sees the 100th anniversary of the event, but it will be the first time two teams will battle it out in a city centre location.

A Navy spokesman said: "This is sport with a crunch. The teams go flat out and the event does genuinely end in blood, sweat and tears."

The teams, from HMS Neptune at Faslane and HMS Caledonia at Rosyth, will be raising cash for the Children's Hospice Association Scotland. They will also take part in the international centenary event in Portsmouth next month.

The historical background of the event goes back to the Boer War when British soldiers were besieged by the Boers at Ladysmith.

Sailors emptied their ships of guns and marched overland to relieve the 118-day siege.

The event in George Square starts just before 11am, with the first race at 11.30am. The others are at 12.30pm and 1.30pm.

As well as the main races, there will also be races by Sea Cadet teams and a history of the event.