A lawyer for Julian Assange on Tuesday accused the United States of "boldly and blatantly" misstating facts about the Wikileaks founder's conduct, on the second day of his extradition hearing in Britain.

Assange faces charges under the U.S. Espionage Act for the 2010 release of a trove of secret files detailing aspects of U.S. military campaigns in Afghanistan and Iraq.

Washington claims the 48-year-old Australian helped intelligence analyst Chelsea Manning to steal the documents before recklessly exposing confidential sources around the world.

But defense lawyer Mark Summers argued much of the 18-charge U.S. indictment Assange will face if extradited was "provably wrong," adding elements were "lies, lies and more lies."

"It's difficult to conceive of a clearer example of an extradition request that boldly and blatantly misstates the facts as they are known to be to the U.S. government," he told a packed courtroom in southeast London.

However James Lewis, a lawyer for the U.S., called the defense's testimony a "series of misstatements about how the indictment is formulated."

He called the Assange team's strategy " a "fundamental mischaracterization of... the allegations."

Assange spent much of the past decade holed up in Ecuador's London embassy to avoid separate legal proceedings in Sweden, but Washington is now seeking his transfer to stand trial.

The extradition hearing at Woolwich Crown Court, next to the high-security Belmarsh prison where he is being held, is expected to last five days before reconvening in May.

Assange, wearing a grey blazer and a sweater over a collared shirt in court, grew visibly tired Tuesday after listening to hours of proceedings -- prompting Judge Vanessa Baraitser to check on his condition.

"Mr. Assange is struggling, he's finding it hard to concentrate," a member of his legal team said after conferring with him.

"He can't communicate with his legal team. He's finding it very difficult."

Earlier, lead defense lawyer Edward Fitzgerald complained that Assange had been stripped naked twice and handcuffed 11 times coming and going from court the previous day.

He warned that his treatment could "impinge on these proceedings" and asked the judge to give "an indication to prison authorities" that the regime should be relaxed.

Baraitser said it was a matter for prison officials, saying she did not have the authority to instruct them on how to treat detainees.

She added that she would expect Assange to be treated fairly and like anyone else.

People's lives "at risk"

Supporters hail Assange as an anti-establishment hero who revealed governments' abuses of power, and argue the action against him is a dangerous infringement of journalists' rights. Critics cast him as a dangerous enemy of the state who has undermined Western security.

WikiLeaks initially worked with newspapers to publish details from the leaked State Department and Pentagon files, which caused a sensation – and outrage in Washington.

In several hours of submissions, Summers said the partnership with media outlets had led to a rigorous redaction process that included liaising with U.S. officials to ensure sources names were not revealed.

"That process involved the U.S. government and State Department feeding suggested redactions to the media," he added.

But Summers said a 2011 book by a journalist from The Guardian revealed the password needed to access the database of unredacted source names and ensured the cache eventually found its way online.

Summers said Assange attempted to warn the U.S. government, calling the White House and attempting to speak to then- Secretary of State Clinton, saying "unless we do something, people's lives are put at risk."

"The notion that Mr. Assange deliberately put lives at risk by dumping an unredacted database is knowingly inaccurate," Summers said.

On the opening day of the hearing Lewis had accused Assange of risking the lives of intelligence sources by publishing classified documents, claiming the U.S. had evidence some had subsequently disappeared.

Rebutting the defense team's claims, Lewis said they were raising "trial issues that have to be determined in the United States.

"It's not the function of this court to enter into a factual determination of these types of issues," he argued.

Assange could be jailed for 175 years if convicted on all 17 Espionage Act charges and one count of computer hacking that he faces.

(With input from agencies)