The top spots were little changed from 2010 with U.S. firm Lockheed Martin still the biggest, U.S. Boeing, overtaking British BAE Systems as number two, and General Dynamics overtaking Northrop Grumman as number four.

SIPRI said a strong recent trend among big arms makers was diversification into cyber-security - protecting computers and networks against intrusions and attacks - as public spending in this area remained a privileged area in Western countries despite budget austerity.

“Diversifying into cybersecurity enables arms-producing companies to widen their civilian customer base, e.g. to reach governmental agencies or private operators of critical infrastructures, and at the same time develop technical competences for electronic warfare for the military market,” it said.

In the 2002-2011 period, arms sales by the top 100 firms grew 51 percent, SIPRI said.