The 53% of companies in Germany have been victims of spying, sabotage or data theft in the last two years, the German IT industry association Bitkom said on Friday.

The organization estimates that the attacks caused around 55 billion euros' worth of damage a year.

A study released by the Bitkom digital association surveyed 1,069 executives and security officers across all sectors.

Several high-profile attacks have occurred recently, such as the WannaCry ransomware attacks in May and a virus dubbed "NotPetya" that halted production at some companies for more than a week. Others lost millions of euros to organized crime in a scam called "CEO Fraud".

Arne Schoenbohm, president of Germany's BSI federal cyber agency, said many big companies and especially those operating critical infrastructure were generally well-prepared for cyber attacks. But many smaller and medium-sized companies did not take the threat seriously enough, he said.

"The high number of companies affected clearly shows that we still have work to do on cyber security in Germany," he said in a statement on Friday.

The BSI urged companies in Europe's largest economy to make information security a top priority and said all companies need to report serious IT security incidents, even if anonymously.

Some 62 percent of companies affected found those behind the attacks were either current or former employees. Forty-one percent blamed competitors, customers, suppliers or service providers for the attacks, Bitkom said.

Foreign intelligence agencies were found to be responsible in 3 percent of the cases, it said.

Twenty-one percent believed hobby hackers were responsible while 7 percent attributed attacks to organized crime.