Conservatives must choose between a dislike of Europe and their responsibility for keeping people safe, South East MEP Catherine Bearder has said.
The Home Secretary has announced the Government is considering whether to pull out of existing European police and justice co-operation measures.
But Catherine has challenged Tories to back measures police and courts use to help catch criminals who flee overseas, tackle international crime and kick out foreign criminals from the UK.
In the Thames Valley, it led to the jailing of paedophile Timothy Edmonds, from Witney, whose child abuse videos appeared on the internet and were spotted by police in Denmark. You can find out more about the case here:
Catherine said measures have been hugely successful in recent years in breaking up paedophile rings, preventing terrorism and bringing criminals who flee across borders to swift justice.
Catherine Bearder: "The Conservatives must choose what is more important: their dislike of all things European or keeping people safe?
"Police say measures like the European arrest warrant are essential for our national security, public safety and leadership in fighting crime and terrorism."
Under terms of the Lisbon Treaty, the UK can decide to opt out of all existing European measures for police and justice cooperation.
And around 100 Conservative MPs want the Government to withdraw from all the measures.
But 13 former UK police chiefs have written to the Prime Minister and Deputy Prime Minister and warned pulling out would put public safety at risk.
Catherine added: "These key international policing measures are used by our police to break up paedophile rings, catch criminals hiding on the Costa del Crime, arrest terrorists and deport dangerous foreign criminals.
"Some Conservatives seem so blinded by an ideological hatred for European cooperation that they would sacrifice the safety of the British public and the rights of victims for it.
"We must put policing before politics. When crime crosses borders, justice must too. Crime is no respecter of borders."
Under the Lisbon Treaty, the Government must decide by July 2014 whether the UK will remain part of all existing pre-Lisbon EU legislation in the field of police and judicial cooperation after 2015.