Swedish police have linked an internet attack which blocked access to several popular Swedish websites to the controversy surrounding WikiLeaks founder Julian Assange.
Mr Assange denies the allegations and says he fears Sweden would extradite him to the United States, which was deeply embarrassed by WikiLeaks's 2010 release of huge caches of US diplomatic cables and confidential documents on the wars in Iraq and Afghanistan.
Supporters of Mr Assange claim he could receive harsh treatment if sent to the US and possibly even face the death penalty.
Swedish police computer expert Anders Ahlqvist said even though it was hard to establish a formal link, the number of internet attacks aimed at Sweden had increased since the case against Mr Assange emerged.
"Every time something happens in the Assange affair, there are more attacks on the internet in Sweden," he said.
"As long as the Assange affair continues, we shall see attacks on Swedish targets".
"I have the impression that an inventory of the state of security of the websites of major Swedish businesses is being drawn up."
The sites of major banks, such as SEB and Swedbank, were affected on Monday, as were those of the national railway company SJ and the TT news agency.
Complaints were filed during the day but have not been centralised, Mr Ahlqvist said, refusing to say whether police had specific evidence pointing to pro-Assange groups.
There have been no claims of responsibility for the attacks.
On September 3, the websites of several Swedish public authorities, including that of the government, were paralysed by a distributed denial of service attack in which sites are overwhelmed by a deluge of requests, putting them out of service.
A pro-Assange group said it was responsible.