NEW YORK’S ATTORNEY General has issued subpoenas to former president Donald Trump and his two eldest children in connection with an ongoing civil investigation into the family’s business practices.

Attorney General Letitia James’ office said in the filing that it is seeking testimony and documents from Trump, Donald Trump Jr and Ivanka Trump “in connection with an investigation into the valuation of properties owned or controlled” by the former president and his company, the Trump Organisation.

Messages seeking comment was left with lawyers for the Trumps and Ms James’ office.

The attorney general’s attempt to get testimony from the former president was reported in December, but the court filing on Monday was the first public disclosure that investigators were also seeking information from Ivanka Trump and Donald Trump Jr.

The Trumps are expected to file court papers seeking to quash the subpoenas, setting up a legal fight similar to one that played out last year after Ms James’ office subpoenaed another Trump son.

Trump sued Ms James last month, seeking to end the investigation after she requested that he sit for a January 7 deposition. Mr Trump’s lawsuit, filed in federal court, alleges that the probe has violated his constitutional rights in a “thinly-veiled effort to publicly malign Trump and his associates”.

Monday’s court filing was the attorney general office’s first public acknowledgement that it has previously subpoenaed Mr Trump’s testimony.

Ms James, a Democrat, has spent more than two years looking at whether the Trump Organisation misled banks or tax officials about the value of assets — inflating them to gain favourable loan terms or minimising them to reap tax savings.

Ms James’ investigators last year interviewed one of Mr Trump’s sons, Trump Organisation executive Eric Trump, as part of the probe. Ms James’ office went to court to enforce a subpoena on the younger Trump and a judge forced him to testify after his lawyers abruptly cancelled a previously scheduled deposition.

Although the civil investigation is separate from a criminal investigation being run by the Manhattan district attorney’s office, Ms James’ office has been involved in both.

Earlier this year, former District Attorney Cyrus Vance Jr gained access to the long-time real estate mogul’s tax records after a multi-year fight that twice went to the US Supreme Court.