The US State Department plans to release tens of thousands of emails by White House hopeful Hillary Clinton from her time as America's top diplomat in batches every 60 days starting from June 30.

In a court filing late on Tuesday, the hub of US diplomacy proposed a rolling schedule to release some 30,000 emails written and received by Clinton during her four years as secretary of state.

The correspondence has triggered a political row after Clinton revealed that in a departure from normal practice she had used a private server and email address during her tenure.

"The department is keenly aware of the intense public interest in the documents and wants to get releasable materials out as soon as possible," Department of Justice officials wrote in the court filing.

The State Department pledged to "strive to produce as many documents as possible on each production date" and within one week after each rollout to tell the court how many pages have been posted.

A first slew of 296 emails relating to Libya and the 2012 attack on the US mission in Benghazi was released on Friday after a district judge last week ordered the State Department to stop dragging its feet.

Diplomats hope to complete the public release of the emails by January 15, 2016.

Clinton turned over paper copies of the emails in 12 cardboard boxes, and says she destroyed all the rest as they were not related to diplomatic matters but were personal.

The correspondence released on Friday did not appear to contain any potentially damaging material, and State Department officials insisted it did not alter the understanding of the Benghazi attack.

Four Americans, including ambassador Chris Stevens, were killed when dozens of heavily-armed militants stormed the Benghazi compound and a nearby CIA facility on September 11, 2012.