Sweden's justice minister said Thursday she wanted to make it easier to prosecute spying activities, a day after revelations that a Swedish diplomat leaked classified EU information to Russia.

• Swedish diplomat accused of spying for Russia

In an interview on public radio, Beatrice Ask lamented the difficulty of prosecuting people who traffic information that is not of a military nature.

"It's difficult for us to prosecute people for activities that seem fairly serious," she said, adding that a committee would be appointed to look into whether the law in this area needed to be changed.

Ask's comments came a day after the Expressen tabloid revealed in a six-page spread that a New York-based Swedish diplomat had at the beginning of the decade given Russia "large amounts of information and documents, especially about how former Soviet states were trying to approach the EU and NATO."

The story, based on an extensive interview with a defected Russian foreign intelligence officer, also quoted prosecutor Tomas Lindstrand who had launched a probe into the espionage charges in 2002.

The investigation was halted after just three months because the information the diplomat had access to was primarily political.

"For it to be considered espionage, I need to prove that the leaked information harmed national security, and that is difficult to prove in this case which involves political information," Lindstrand told Expressen.

Ask said Thursday Swedish law might need to take into account "grey areas that are perhaps not strictly speaking military, but that involve industry or other things, and that can also ... pose a threat to Sweden."

When it came to "some systematic information-gathering activities ... it is hard to find a legal framework that can be used," she said, adding that "it should thus be considered whether this is something that should not be criminalised by law."