New legislation in the US Congress targets WikiLeaks founder Julian Assange for espionage prosecution.

Representative Peter King, a New York Republican, introduced the Securing Human Intelligence and Enforcing Lawful Dissemination, or SHIELD, Act on Tuesday. The bill would clarify US law by saying that it is an act of espionage to publish the protected names of American intelligence sources who collaborate with the military or intelligence agencies.

King introduced similar legislation in 2010. Senators John Ensign, Joe Lieberman and Scott Brown, introduced similar legislation in the Senate last week.

King has called on US Attorney General Eric Holder to prosecute Assange for espionage. The new bill would give the US Department of Justice greater authority for prosecuting intelligence leaks, King said in a news release.

"Julian Assange and his associates who have operated and supported WikiLeaks not only damaged US national security with their releases of classified documents, but also placed at risk countless lives, including those of our nation’s intelligence sources around the world," King said in a statement.

Some WikiLeaks associates are planning a new website called OpenLeaks, "dedicated to the same dangerous conduct," King added. "These organisations are a clear and present danger to the national security of the United States. Julian Assange and his compatriots are enemies of the US and should be prosecuted ..."

Critics of the SHIELD Act have said it appears to be aimed at publishers, not leakers.