The Supreme Court, Sweden's highest court, said it would not grant leave for Assange to appeal against a lower court ruling on his arrest, the BBC reported Thursday.
About two weeks ago, the Swedish prosecutor's office said a court in Stockholm approved its request for Assange's arrest so he could be questioned on charges of rape and other sexual offenses stemming from a trip he made to Sweden in August. Assange has denied the accusations.
The development comes after WikiLeaks offered for publication more than 250,000 U.S. State Department cables to several newspapers. The documents included communications about U.S. policy in Iran, Pakistan, Korea and elsewhere.
Interpol has issued a "red notice" for Assange, 39, to 188 countries. British media have reported that law enforcement authorities believe Assange is in Britain but haven't acted yet on an international detention warrant.
Assange's exact location remains unknown but he frequently visits Britain, and reportedly is in hiding near the capital, The Daily Telegraph reported.
Mark Stephens, Assange's British lawyer, said he hasn't been contacted by Interpol or police. He said Wednesday the red notice was a "persecution and prosecution" of his client, and Swedish authorities had ignored repeated requests from Assange to meet, the Telegraph said.
"It is highly irregular and unusual," Stephens said. "Mr. Assange has repeatedly sought meetings with the (prosecutor) ... to answer her questions and clear his name."
He said he also was investigating whether the Swedish prosecutor's application to have his client held incommunicado "is in any way linked to this matter and the recent, rather bellicose U.S. statements of an intention to prosecute Mr. Assange."