A military judge has refused to dismiss all charges against the US Army private accused in the biggest leak of government secrets in the country's history.

Colonel Denise Lind denied the defence application during a pre-trial hearing in the court-martial of Bradley Manning.

Manning is accused of sending hundreds of thousands of sensitive documents to the anti-secrecy website WikiLeaks.

The ruling means the hearing will continue and is scheduled to run through to Thursday.

The defence has filed a separate motion seeking dismissal of the most serious charge, aiding the enemy. That offence carries a maximum penalty of life imprisonment.

Col. Lind scheduled the trial to run from September 21 to October 12.

Manning's lawyers had argued that prosecutors were so slow in sharing required information with the defence that the only remedy was to throw out the charges.

Prosecutors maintained that they needed time to obtain documents from civilian agencies and search the records for relevant material.

The 24-year-old Manning was ordered court-martialed after he was accused of downloading documents, diplomatic memos and video clips and sending them to WikiLeaks. He was working as an intelligence analyst in Baghdad when authorities say he copied classified material from government computers in late 2009 and early 2010.

The material WikiLeaks published included cockpit video of a 2007 US Apache helicopter attack that killed a number of civilians, including a Reuters news photographer and his driver. The US government says the civilian deaths were accidental.

Manning has been in jail since he was charged in May 2010. His treatment at a Marine Corps base, where he was confined 23 hours a day in a single-bed cell, caused support for him to swell in the US and overseas.