UKIP Defence Spokesman Mike Hookem MEP has written to Theresa May asking her to explain the Home Office decision that refused leave to remain to former soldier Semesa Maiyale.
The former soldier said Mr Maiyale had "proved his dedication to this country after being recruited by the British Army from a Commonwealth country and taking the oath of allegiance to Her Majesty."
Mr Hookem said that telling a potential recruit they would be entitled to stay in the UK after four years of military service then refusing to let him stay was "beneath the reputation of the United Kingdom."
He also questioned Mrs May's policy in prefering uncontrolled migration from the EU but refusing permission to qualified, hard working migrants who, he said, "the overwhelming majority of the British public would prefer."
"I am well aware that it is the position of this government to remain in the European Union with unrestricted right of movement to criminals, including the suspected murderer of Alice Gross who previously murdered his wife before moving to this country."
"I cannot understand why you would prefer people like Arnis Zalkalns to live in the UK and refuse permission to Mr Maiyale," he wrote.