One murder in five in England and Wales is committed by a foreigner, police figures released to The Sunday Telegraph show.

Out of 461 people convicted of or charged with homicide in the 12 months up to April last year, 96 were foreign citizens - from 28 different countries.

The findings again highlight Britain's failure to deport foreign criminals, a focus of government attention since the blunder that led to the sacking of Charles Clarke as home secretary in 2006.

Recent murderers have included foreigners who had been convicted of robbery and assault but were allowed to remain in Britain after serving their sentences.

Police chiefs seized on the 2006/7 figures - the last year for which full data are available - to warn that immigration was having a "significant impact" on Britain, and putting forces under rising strain. The information also provides evidence that foreign criminal networks have built up extensive UK operations.

Scotland Yard said half of the organised crime gangs in London were "ethnic" - bound by a common language or homeland. The most common nationalities for foreign killers were Pakistani, Indian and Jamaican.

Foreigners were also more likely to become victims. According to the figures, 15 per cent of those who died were from overseas, even though foreigners account for only six per cent of the British population. In many cases, both victim and killer were from the same immigrant community.

David Davies, the Conservative MP for Monmouth, said: "These extraordinary figures demonstrate the failure of the Government's immigration policy, which has seen all sorts of undesirable characters being able to get into this country and then stay here using the Human Rights Act to escape deportation."

Sir Andrew Green, the director of the think tank MigrationWatch, said: "This underlies the importance of removing foreign prisoners at the end of their sentence, lest they go on to commit still more serious offences."

All 43 police forces in England and Wales were asked, under Freedom of Information laws, for nationalities of offenders and victims for all homicides in 2006/7. Most cases were murder, a few manslaughter. Responses were received from 36 forces, of which 25 supplied figures.

The picture remains incomplete because some murders are still unsolved, and because some forces excluded cases awaiting trial. Nevertheless, the figures cover more than half of the 755 homicides in England and Wales in 2006/7.

Among the most high-profile cases was that of Roberto Malasi, an 18-year-old Angolan asylum-seeker who stormed into a christening party in Peckham, south-east London, and shot dead a 33-year-old woman as she cradled her baby niece, before robbing guests.

His three Nigerian accomplices all had past convictions. Malasi went on the run and, two weeks later, stabbed to death an 18-year-old pastor's daughter who he felt had "disrespected" him. He is serving life for the murders. Other notorious foreign killers have included:

• Yusuf Jama, a Somali asylum-seeker, was in the gang that shot dead Pc Sharon Beshenivsky in Bradford in 2005;

• Michal Pech, a Slovak army deserter, who shot dead his former lover, Clare Bernal, at Harvey Nichols department store in London in 2005, before shooting himself;

• David Bieber, an American bouncer wanted for murder in his homeland, who shot dead Pc Ian Broadhurst in Leeds in 2003;

Julie Spence, the Cambridgeshire chief constable, has led complaints about the cost of investigating and prosecuting murders involving immigrants. While the average murder costs police and courts £1.5 million, an overseas link means extra spending on translators and travel.

Jon Stoddart, Chief Constable of Durham and lead on homicide for the Association of Chief Police Officers said: "Migration has had a serious impact on the UK population over the past 10 years and with that have followed changes in the demands made on the police service. There are also specific resource implications, including the demand for the police service to use interpreters and where necesary pursue investigations across borders. There can also be difficulties arising from cultural differences."

Detectives must also grapple with issues such as clan feuds and "honour" killings. Scotland Yard has focused on organised gangs in the Turkish, Chinese, Vietnamese and Colombian communities.

The figures show a wide variation between areas. In London, 76 out of 231 identified killers were foreign nationals; in Manchester, eight out of 42; in Bedfordshire, three out of seven; but in West Yorkshire, none out of 47.

The Home Office said that the UK Borders Act, which takes effect in July, would make it easier to deport foreign criminals.

"We are absolutely clear that any foreign criminal convicted will be held accountable and expelled from Britain," said a spokesman.