A few weeks ago, Serhiy was a business analyst at an IT company. Zakhar was a civil engineer. Now they are soldiers, training to liberate Ukraine from Russia's invasion — but doing it more than 1,000 miles (1,600 kilometres) away in Britain.

They are among several hundred Ukrainian recruits pounding through an intense form of infantry training at an army base in southeast England. One batch of the 10,000 Ukrainian soldiers that the British military has pledged to train within 120 days, they are spending several weeks learning skills including marksmanship, battlefield first aid and - crucially for their country's future — urban warfare.

As the Ukrainians practice house-clearing amid the rattle of gunfire and pall from smoke grenades on a mock-townscape where British soldiers once trained for operations in Northern Ireland, they think about driving Russian troops from the streets of their own cities.

"The most important part is urban training, because it's the most dangerous combat, in cities," said Serhiy, who like the other Ukrainians did not want his full name used because of security concerns. "The British instructors have a lot of experience, from Iraq, Afghanistan. We can adapt all this knowledge to the Ukrainian situation and use it to liberate our country from Russian invasion."

British trainers are putting the Ukrainian troops through a condensed version of the British Army's infantry training, covering weapons handling, first aid, patrol tactics and the law of conflict. The aim is to turn raw recruits into battle-ready soldiers in a matter of weeks. The first batch arrived last month and has already been sent back to replenish depleted Ukrainian units.

"We are running a basic infantry course, which takes Ukrainian recruits and teaches them to shoot well, to move and communicate well within any tactical environment, and to medicate well," said Major Craig Hutton, a Scots Guards officer helping to oversee the training.

Ukrainian volunteer military recruits take part in an urban battle exercise whilst being trained by British Armed Forces. Photo / AP

Hutton says many of the Ukrainian troops have little military experience but "they are so motivated. They have a fantastic will to learn, and they just want to practice, practice and practice more."

More than 1,000 UK personnel are involved in the training mission, taking place at four bases around the UK. Other countries are also sending trainers, including Canada, the Netherlands, New Zealand and the Nordic nations.

Britain is sending the Ukrainians home with new uniforms, body armour, helmets and other gear, part of 2.3 billion pounds (USD$4.36 billion) worth of UK military aid to the country that also includes anti-tank missiles and sophisticated rocket-launch systems.

Zakhar, the former engineer, said it was hard to be away from Ukraine as fighting rages in the eastern Donbas region and in the south.

"I left my parents. I left my brothers and sisters, my relatives, to gain knowledge and experience that will help me … free our territory from occupiers and invaders," he said through an interpreter.

Ukrainian volunteer military recruits take part in an urban battle exercise whilst being trained by the British Armed Forces. Photo / AP

Serhiy, the one-time IT worker, has been in uniform for less than a month and is equally determined.

"I know that Ukrainian soldiers are dying to protect our homes right now. So it's hard to know that I am not with them," he said. "But the Ukrainian army needs only professional soldiers, so I am ready to train as hard as possible to be ready for the battle ahead."

Brigadier Justin Stenhouse, who is in charge of the training as commander of the 11th Security Assistance Brigade, said seeing the motivation of the Ukrainians is "humbling."

But he acknowledged that preparing for the chaos of urban combat is "almost impossible to do in training." The goal of the mission, he said, is to "train them so that they can adapt to survive in those early weeks of combat."

"They will learn more in the first weeks of combat than we can possibly give them here," he said.

- AP