In an interview with Radio Sweden, Karlsson said he feared the Social Democrats would seek to depict his party and its supporters as influenced by Russia, or even as active agents or spies.
There is a real risk... that the Social Democratic government are using Russia as a means to try to silence the opposition, and trying to make everybody who doesn't share their political views suspect of being a Russian spy."
Sweden’s Prime Minister Stefan Löfven on Monday announced a string of measures designed to prevent foreign countries interfering in the 2018 campaign, following claims that Russia had tried to influence the outcome of last year’s presidential poll in the US.
Anders Norlén, the Moderate Party MP who chairs the parliament's constitutional committee, told Radio Sweden on Monday that parties should be careful to avoid benefiting from Russian propaganda or other support.
"Every party in the Swedish parliament has a responsibility to make sure that the facts they use and the arguments they use are sound and valid and not just a way of repeating propaganda from, for instance, Russia," he said.
Karlsson said he accepted that measures needed to be taken to safeguard the election.
“I think that it’s likely that Russia and maybe other countries are trying to influence Sweden in some way,” he said. “We should of course give Säpo the resources they need to try to stop real spies, to try to stop infiltration in some ways.”
In the interview, he also defended Moderate party leader Anna Kinberg Batra, who will on Saturday face party activists after a string of polls showed that her party had lost significant support.
Several Moderate politicians have blamed the party’s recent difficulties on her decision in January to open talks with the Sweden Democrats in parliamentary committees.
“It was not a mistake. She couldn’t do anything else,” he said. “Liberals in Sweden haven’t yet understood that there is not the option of a liberal majority. It doesn’t exist. They have to choose between us and the Social Democrats. When that dawns on the liberals on Sweden, many will have a more forgiving view of the decision of the Moderate Party."
Karlsson also said he welcomed the Centre Party’s proposal to attempt to block tax rises proposed by the Social Democrats with the passive support of the Sweden Democrats.
“This would be better than nothing, but why not talk to us, and why not agree on a complete budget?" he said.
"We could change many things besides these taxes and have a completely different government. We haven’t had such a large non-socialist majority in parliament for decades, and still we have a socialist government,” Karlsson said.