Speaking in the House of Commons, UK Defence Secretary Michael Fallon said the training mission, which will begin in mid-March, was "closely defined" and was being undertaken at the request of the Ukrainian government.
He said: "We are not deploying combat troops to Ukraine and will not do so," when asked whether the deployment of military personnel would provoke so-called "mission creep".
British Prime Minister David Cameron has confirmed that the UK will send up to 75 military personnel to Ukraine within the next month to help train local Ukrainian forces.
"Over the course of the next month we are going to be deploying British service personnel to provide advice and a range of training, from tactical intelligence to logistics to medical care, which is something else they have asked for," Cameron said.
"We will also be developing an infantry training programme with Ukraine to improve the durability of their forces. This will involve a number of British service personnel, they will be away from the area of conflict but I think this is the sort of thing we should be helping with," he said.
Britain Does not Rule Out Further Equipment for Ukraine
Fallon said British personnel would conduct the training in Kiev and western Ukraine. But he admitted Britain was considering a Ukrainian request for equipment and supplies, but had no plans to provide "lethal" assistance to Kiev.
However, during a heated debate in Westminster, veteran Labour MP Dennis Skinner said:
"Mission creep knows no boundaries. Vietnam started with just a little request. As sure as night follows day, Ukraine will realise the UK is a participant in the battle and ask for more. What's he going to do then?"
Fallon said: "We are considering a further request for additional equipment and support. That is non-lethal, but we do reserve the right to keep that under review."
Senior Conservative MP Sir Edward Leigh, warned the Defence Secretary: "The trouble with sending advisers is that, as the Americans found in Vietnam, and as many other nations have found since, mission creep eventually results in the sending of combat troops. Given that Ukraine is an area the size of France, where whole German armies of tens of thousands of men were enveloped and destroyed in the Second World War, is there not a real danger of that?"
Fallon admitted that the UK had been advising the Ukraine government for some time on military tactics. "We already provide advice and support on how to tackle corruption inside the Ukrainian Government. We have done so over the past few months and, indeed, I think even before then.
"As for mission creep, may I make it absolutely clear that we are not deploying combat troops to Ukraine, and we will not do so. We are providing non-lethal assistance that has been requested by the Ukrainian Government to enhance the capability of their armed forces and to attempt to reduce the number of fatalities and casualties that they have suffered."
Former Defence Secretary Liam Fox urged Fallon to offer the Ukrainian Government military hardware, saying: "They require equipment such as unmanned aerial vehicles for reconnaissance and targeting. They require anti-tank capability and encrypted communications."
Fallon replied: "We are supplying defensive equipment. It might not be lethal, but it does help the Ukrainian armed forces better defend themselves. As I said in my initial statement, in addition to the secondment of 75 trainers we are considering a further request from the Ukrainian Government for additional equipment and support."