The Internet sites of both Chancellor Angela Merkel and the Bundestag were both out of action on Wednesday morning, with a pro-Russian hacking group claiming responsibility.

The websites of Germany's lower house, the Bundestag (www.bundestag.de), and Merkel's official chancellery (www.bundeskanzlerin.de) both failed to load, with the group CyberBerkut claiming to have carried out the attack in connection with a visit to Berlin by Ukrainian Prime Minister Arseniy Yatsenyuk.

CyberBerkut said Yatsenyuk was in Berlin to borrow money to finance the military campaign against pro-Russians in the east of Ukraine.

"Yatsenyuk needs money to extend the war and not to restore collapsed infrastructure of our country. This war has already taken thousands of lives, and Yatsenyuk will kill more for your money!" a message on CyberBerkut's website read.

The attack, which downed the sites from 9 a.m. (1000 UTC), was confirmed by Merkel's office. "There is a heavy attack on our provider's servers, caused by multiple external systems," Seibert said in Berlin, adding that he could not give details about those responsible.

Berkut is the name given to the special forces loyal to Ukraine's Russian-leaning former President Viktor Yanukovych, accused of killing nearly 100 Ukrainian civilians in unrest before the president was deposed.