WASHINGTON, May 25, 2011 -- WikiLeaks founder Julian Assange today called the nearly year-long detention and forthcoming government prosecution of Army Pvt. Bradley Manning an attempt to "terrorize whistle-blowers" but said it has failed to have a chilling effect.

The Pentagon has accused Manning, who has been held in a military brig since May 26, 2010, of supplying hundreds of thousands of secret government documents to WikiLeaks. He is expected to be formally charged this summer and possibly tried in the fall.

"There is no doubt the U.S. government has tried to terrorize whistle-blowers into not revealing important information to the public," Assange told reporters on a conference call from his house arrest in the United Kingdom, where he's awaiting trial on sex-crimes charges.

Asked by ABC News if that effort had scared off potential sources from sharing materials, Assange said the opposite was true.

"Courage is contagious. We have seen a dramatic increase in the number of sources willing to come forward," he said. "Fear no doubt is also restraining their activities. ... But there is an increased supply of materials coming to us."

While Assange denies knowing the source behind the controversial WikiLeaks documents, he has defended Manning as a victim of alleged government repression and mistreatment.

"The treatment of Bradley Manning and the witchhunt for other possibly connected individuals around Boston seems to be part of that endeavor," he said, referring to the U.S. government's attempts to deter future leaks.

Manning had been held in solitary confinement at a Marine Corps detention center in Quantico, Va., where he is forced to spend all but one hour a day in his cell, exercise in chains, stripped naked every night and forced to wear what his attorney described as a scratchy, suicide-proof smock.

A chorus of international critics said the conditions amounted to inhumane treatment, a charge the military disputes.

Last month, Manning was transferred to Fort Leavenworth, Kansas, and a state-of-the-art Joint Regional Correctional Facility. The Pentagon said the move was not prompted by the outcry over conditions at Quantico but was instead intended to provide Manning with greater access to resources that could improve his mental, emotional and physical health.

Manning now shares a quad cell with three other men, receives three hours of exercise each day, including one outside, and shares meals with other inmates, said Kevin Zeese, an attorney with the Bradley Manning Support Network.

In March, the Army filed 22 new counts against Manning, which included aiding the enemy, theft of public property or records, computer fraud and transmitting information in violation of the Espionage Act. Manning could face the death penalty or life in prison if convicted.

WikiLeaks Partnerships Grow

Assange said Manning's case and U.S. government threats to prosecute WikiLeaks have not slowed expansion of the organization.

WikiLeaks now has partnerships with more than 73 media organizations worldwide to disseminate and publish controversial information from secret government cables in more than 50 countries, Assange said.

"In the last month in English alone there have been over 8,700 articles written about our materials," said Assange. "We're expanding our network of cooperative institutions by approximately four per week and going into publishing."

The website, which was founded in 2006, has so far selectively released around 12,000 of more than 250,000 secret documents in its possession.

Assange also credited WikiLeaks work with triggering a "year of miracles for journalism" that has enhanced the transparency of the U.S. and foreign governments and contributed to the democratic revolutions sweeping across the Arab world.