Military officials, high ranking civil servants in the government, and seven ministers are aware of the plan, Sveriges Radio (SR) reported.
Both Foreign Minister Carl Bildt and Trade Minister Ewa Björling claim, however, that they are unaware of any such plan.
Citing classified documents, the broadcaster claims that both Bildt and Björling, as well as Prime Minister Fredrik Reinfeldt, received a letter from the Swedish ambassador in Switzerland, Per Thöresson, describing the plan.
Among other things, the letter details how the embassy "is arranging interviews and pitching positive articles about Sweden" to the Swiss press.
However, Thöresson describes the actions as "regular embassy work".
"It's not a list to influence opinion; it's a list of events we have planned," he told SR.
The broadcaster reported that Swiss Defence Minister Ueli Maurer asked for the Swedes for help in winning a May 18th referendum on the country's purchase of Swedish-made Gripen fighter jets. Outreach efforts are meant to reach all Swiss voters, with Maurer requesting Gripen demonstration flights every six weeks, include a showing at World Cup skiing races planned in March.
In a December 17th letter to colleagues in Stockholm Thöresson wrote, "Now it's 'only' about winning the referendum," according to SR.
A month earlier he wrote, "Considering how uncertain the outcome of the referendum is, our contribution can very well be what tips the scales."
In 2011, the Swiss government approved the 3.13 billion Swiss francs ($3.47 billion).deal. But opponents forced a referendum on the Gripen purchase after submitting more than 65,000 valid signatures expressing their disapproval.
Polls show a majority of voters oppose the deal, which cannot be blocked as such. But under Switzerland's rules, opponents can contest the law on funding the purchase by tapping an annual 300 million Swiss francs from the military's budget over 10 years.
Sweden's ambassador emphasized his letter should be interpreted "exactly as it's written".
"Everything points to this being a very close referendum. It's not at all strange then that we implement our plan as planned," he told SR.