The states of Bahrain, Qatar, Kuwait, Oman, Saudi Arabia and the United Arab Emirates, which form the Gulf cooperation council, spent between them €1.42 billion on German arms in 2012.
This was a huge increase from the 2011 figure of €570 million. The information was released by the Economy Ministry in response to a written parliamentary question submitted by the socialist Left party, the Süddeutsche Zeitung reported on Friday.
The biggest arms customer of the region was Saudi Arabia which spent €1.24 billion in 2012 alone - nine times the amount it spent on German weapons the year before.
German business with Saudi Arabia is highly contentious because of the kingdom's poor domestic human rights record and its intervention in neighbouring Bahrain two years ago to help the government there put down protests.
"The Gulf states continue to arm themselves, and the government has absolutely no compunction about arming them to the teeth," said Jan van Aken, an MP from The Left party.
He said the fact that Saudi Arabia was by far the leading customer for the German arms export industry clearly showed "that the most grave human rights abuses are obviously no longer any reason to refuse exports."