NEW YORK  - An unnamed American law firm was caught up in surveillance involving the US National Security Agency and its Australian counterpart, according to a report released on Saturday.

The New York Times reported that a top-secret document obtained by the former NSA contractor Edward Snowden showed the firm was monitored “while representing a foreign government in trade disputes with the US”.

According to the Times, the government of Indonesia retained the law firm for trade talks which were under surveillance by the Australian Signals Directorate. The Australian agency offered to share information with the NSA.

While the law firm wasn’t identified in the document, the Times said Mayer Brown, a Chicago firm with a global practice, was advising the Indonesian government on trade issues at the time.

The Times said the NSA declined to answer questions related to the document.

Duane Layton, a Mayer Brown lawyer involved in the trade talks, told the Times he did not have any evidence Australian or US intelligence agencies had been spying on him or his firm.”I always wonder if someone is listening, because you would have to be an idiot not to wonder in this day and age.”

Last year, Snowden leaked thousands of documents to media outlets including the Guardian and the Washington Post. One of the journalists to whom he leaked the documents, Laura Poitras, was bylined on the Times piece.

The document obtained by Snowden, a monthly bulletin from the NSA’s liaison office in Canberra, was dated February 2013 and noted that “information covered by attorney-client privilege may be included” within the information being offered. Liaison officials asked for guidance from the NSA general counsel’s office.

The newspaper also quoted from the document that the Australian agency was “able to continue to cover the talks, providing highly useful intelligence for interested US customers”.

The NSA is not allowed to target American citizens or businesses for surveillance without a warrant, although it is allowed to intercept communications between Americans and foreign intelligence targets. Information disclosed by Snowden has included the NSA’s collection of the telephone records of millions of Americans.

The agency has also come under fire for eavesdropping on heads of state, including the German chancellor Angela Merkel, and for working in industrial espionage.

In November 2013, it was reported that the NSA and its Australian counterparts had worked together on a surveillance operation covering a 2007 United Nations climate change conference in Indonesia. The report caused the Australian government considerable diplomatic embarrassment.