A senior Conservative backbencher says all asylum seekers entering the UK should be detained until full background checks have been carried out.
Lee Anderson, who sits on the Home Affairs Committee, says he was horrified at the murder of an aspiring Royal Marine by an Afghan asylum seeker who was also wanted for two other murders in Serbia and had been convicted for previous drug offences in Italy.
Lawangeen Abdulrahimzai had lied to officials, claiming he was just 14 when he arrived in the UK when in fact he was an adult.
Abdulrahimzai stabbed 21-year-old Thomas Roberts to death in Bournemouth after an argument over an e-scooter in March, last year.
Abdulrahimzai, also 21, had admitted manslaughter but the jury at Salisbury Crown Court found him guilty of murder.
After delivering their verdict, the jury heard Abdulrahimzai had previously been convicted of the murder of two people in Serbia and had been sentenced to 20 years in prison in his absence.
It has also emerged that before travelling to Serbia he had been denied asylum in Norway after being convicted of drug dealing there.
In a statement, the Home Office said: "Foreign National Offenders who exploit our system and commit crimes here in the UK will face the full force of the law, including deportation at the earliest opportunity for those eligible.
“The government is committed to stopping abuse of the immigration system, taking decisive action against those who try to play the system.”
But criticising the vetting of asylum seekers, Tory backbencher and Home Affairs Committee member Lee Anderson said: "I've been saying from day one, anybody arriving here illegally should be detained and detained until we can fully decide who they are, where they've come from and if they've got legitimate asylum claim.
"If not, keep them detained. In detention centres, that not too difficult to do."
Abdulrahimzai, who lived in Poole at the time of the murder, arrived in the UK in December 2019, and told the authorities he was 16 when he was arrested, but the UK authorities have since determined that he is now 21.
Speaking to LBC, Home Office Minister Chris Philp said new "scientific age assessments" like scanning immigrants' wrists would be introduced to stop adults illegally entering as children. He said the murder of Thomas Roberts is a "very powerful illustration" of why methods used in other European countries should be adopted here.
In the months before the incident, Abdulrahimzai shared pictures of himself posing with a knife on the social media and video sharing app TikTok.
He had been seen carrying a knife by his foster parent, who had warned him not to, and had also been warned by police and social workers of the dangers of carrying a knife.
Abdulrahimzai told the court that he carried a knife because he was “fearing” for his life because there were people from Afghanistan who wanted to kill him, and he had also had death threats in Bournemouth.
The defendant said he posted photos of his knife on TikTok to get followers from “people out there liking knives”.
The court heard his parents had been killed and he had been tortured by the Taliban so he carried a knife for his own protection.
In a statement Mr Roberts’ family said: “The family of Thomas Roberts cannot describe the loss of their son, brother, partner, friend in the tragic circumstances of his violent and unnecessary death.
“He had a potentially fulfilling future to look forward to, whether that be in his profession of precision engineer or his potential in the military.
“Thomas was a normal kind person, who had enjoyed life. On the night of his tragic death, he was in town with friends having a good time when he was suddenly involved in an incident involving a large knife that cost him his life."
Abdulrahimzai will be sentenced at Salisbury Crown Court on Wednesday.