A man who worked for the US government has been charged with leaking classified information assessing Israel's earlier plans to attack Iran, according to court papers filed Wednesday.

The man, identified as Asif William Rahman, was arrested by the FBI this week in Cambodia and was due to make his first court appearance in Guam.

He was indicted last week in US court in Virginia on two counts of willful transmission of national defence information — felony charges that can can carry significant prison sentences.

It was not immediately clear whether Rahman had a lawyer or which federal agency employed him, but officials say he had top secret security clearance.

The charges stem from the documents, attributed to the National Geospatial-Intelligence Agency and National Security Agency, appearing last month on a channel of the Telegram messaging app. The documents noted that Israel was still moving military assets in place to conduct a military strike in response to Iran's blistering ballistic missile attack on October 1.

Israel carried out a retaliatory attack on multiple sites in Iran in late October.

The documents were sharable within the “Five Eyes,” which are the United States, Britain, Canada, New Zealand and Australia.

The New York Times was first to report his arrest.