It said the agreement was reached at a meeting in Stockholm at the weekend
with WikiLeaks founder Julian Assange.
"We welcome the help provided by the Pirate Party," Assange was quoted as saying in the statement. "Our organisations share many values and I am looking forward to future ways we can help each other improve the world."
WikiLeaks has provoked a media tempest and the ire of the Pentagon for releasing 76,000 classified US documents about the war in Afghanistan. It is set to release in a couple of weeks another 15,000 documents that are likely to be even more sensitive.
The Swedish Pirate Party, created in 2006 to campaign for more freedom on the Internet, scored a breakthrough in the 2009 European elections by taking 7.1 percent of the vote in the Scandinavian country.
The party is running in the parliamentary election slated for September 19th, but opinion polls show its support has faded.