PROSECUTORS must prove that US Army private Bradley Manning intended to help al-Qaeda by passing secret government documents to the WikiLeaks website, defence lawyers argued on Monday.

Manning's civilian attorney questioned the heart of the government's case at a pretrial hearing, contending that prosecutors had to show more than mere "negligence" to win a conviction for the serious offence of "aiding the enemy". The government had to prove Manning "intended to engage the enemy" by allegedly leaking sensitive files to a website, David Coombs said. Otherwise the trial would ignore the realities of the internet era and anyone who passed classified information to a newspaper could be accused of treason because adversaries have access to the web.

Citing a hypothetical example, Coombs asked how the court would rule if someone passed information to the New York Times. "The enemy can read the New York Times like anyone else," he said. "Have I now given information to the enemy?" After defence lawyers and prosecutors sparred over the issue, Judge Denise Lind said she would draft instructions to a future jury that would take into account arguments from both sides.

Manning, 24, could spend the rest of his life in prison if convicted of aiding the enemy by handing hundreds of thousands of classified documents - including military logs from Iraq and Afghanistan and US state department diplomatic cables - to the WikiLeaks website.

Prosecutors maintain they only have to prove that Manning knew al-Qaeda might see the sensitive intelligence files posted by WikiLeaks, given his training as a military intelligence analyst.

Prosecutor Capt Joe Morrow said the government was asserting that Manning had "knowledge of a very definite place" when he allegedly handed over a trove of files, a reference to the WikiLeaks website. But the defence argues the government has to demonstrate Manning "knowingly and intentionally gave intelligence to the enemy".

"Today, everyone understands that information posted on a publicly accessible website can potentially be viewed by anyone with internet access," the motion said.

The case has highlighted difficult legal questions raised by new technology, with the court struggling to apply laws that have failed to keep pace with digital advances. At Monday's hearing, Manning's lawyer also argued his client had permission to download secret diplomatic cables and should not be charged with an electronic "break-in" of state networks.

Coombs asked for the dismissal of two counts against his client, saying Manning did not steal a password or otherwise hack into a government computer network when he downloaded classified state department cables.

Accusing prosecutors of failing to recognise "uncomfortable facts", Coombs said Manning had free access to the diplomatic cables and never circumvented any "electronic gate". But the prosecution said the "Wget" software he used, which is designed to retrieve computer files quickly, was not authorised and that Manning's actions therefore amounted to "trespass". Coombs acknowledged that Manning could be charged with a lesser offence for using the software, which he said was akin to a worker violating contractual terms set down by a company for computer use.