A sharp reduction in pirate attacks off Somalia is "incontrovertible proof" that European Union membership helps Britain achieve its security priorities, shadow defence secretary Emily Thornberry has claimed.
Ms Thornberry highlighted figures from the EU's Operation Atalanta counter-piracy mission, which showed that the number of attacks on ships fell from a peak of 176 in 2011 to two in 2014 and none at all in 2015.
Some 47 ships or crews were seized by pirates in 2010, but numbers have dwindled sharply and the last successful attack was in 2012. From a high of 736 hostages and 32 ships being held by pirates, numbers dropped last year to 26 hostages and no ships being held.
Following a visit to Atalanta's home base at Joint Forces Command in Northwood, Middlesex, Ms Thornberry said: "We all remember the havoc and fear being caused by piracy just a few years ago, including British citizens being taken hostage. The potential economic damage to the UK in terms of lost trade, higher insurance and other costs was huge.
"But now, as a result of Operation Atalanta, we have gone well over a year without an attack, and more than three years without any ships or crews being seized.
"That is not something we could have achieved on our own, and it is a powerful reminder that it is only through collaboration and co-operation with our European partners that we can tackle the shared international challenges we face.
"For those who believe we could protect our interests outside the EU, I ask them to look at this incontrovertible proof of the vital difference that EU co-operation makes to the achievement of our defence objectives, and urge them to think again."
The EU launched Operation Atalanta in December 2008 within the framework of the European Common Security and Defence Policy to deter and disrupt piracy and armed robbery at sea and protect vulnerable shipping off the coast of Somalia. Its mission is due to continue until the end of this year.