OSLO: The Norwegian parliament suffered a cyber attack in the past few days and the e-mail accounts of several elected members as well as employees were hacked, the national assembly and a counter-intelligence agency said on Tuesday.

"Our analysis shows that various quantities of data were downloaded," the parliament said in a statement, without identifying the affected lawmakers and staff.

The Norwegian National Security Authority (NSA) assisted in countering the attack. "We have been involved for a few days," NSA spokesman Trond Oevstedal said. "We are assisting parliament with analysis and technical assistance."

It was not immediately clear who was behind the cyber attack, or what type of attack it was.

Efforts to halt the attack had "an immediate effect", said Marianne Andreassen, the parliament's non-elected chief administrator.