Police officers secure a scene in Salisbury, England. Picture: Matt Dunham/AP

London - The number of homicides in England and Wales hit their highest level in a decade, official statistics showed on Thursday, as authorities struggle to halt a surge in fatal stabbings.

The Office for National Statistics said homicides - which includes murders and manslaughter - had been rising since March 2014, in contrast to falling numbers over the previous decade.

While still rare in Britain, the sharp rise in murders, especially from knife-crime, has put pressure on Prime Minister Theresa May, whose government has been focused on trying to leave the European Union.

The government said it had given police extra powers and billions of pounds of extra funding.

"Too many people are still falling victim to serious violence, which is why we will continue our urgent and unprecedented action to reverse this terrible trend," junior minister Nick Hurd said.

The opposition Labour Party said the government was "in denial" about the impact of police funding cuts.

Reductions in police staffing levels during May's time as interior minister were a big issue during campaigning for the 2017 election, at which she lost her majority.

Since then, the number of homicides has increased further.

Police-recorded statistics showed a 6 percent rise in homicides to 732 in the year ending December 2018, the highest levels since the year to March 2008.

The figures for 2017 were pushed up by militant attacks in London and Manchester which killed 36 people.

Excluding casualties from those attacks, there was a 12 percent increase in homicides in 2018.

Official statistics published last month showed there were 285 fatal stabbings in England and Wales in 2018, the highest level since records began more than 70 years ago.

Police say the surge in knife crime in a country where guns are hard to obtain has been driven by several factors, including rivalries between drug gangs, cuts to youth services and provocations on social media. 

Reuters