Former US President Donald Trump has declined to answer questions as part of a New York state investigation into his family's business practices.

Mr Trump had sued in an effort to block the interview at the New York attorney general's office on Wednesday.

State officials accuse the Trump Organization of misleading authorities about the value of its assets in order to get favourable loans and tax breaks.

Mr Trump denies wrongdoing and has called the civil probe a witch hunt.

An hour after he was pictured arriving at the Manhattan office where he was questioned under oath, Mr Trump released a statement in which he criticised New York Attorney General Letitia James and the broader investigation.

"Years of work and tens of millions of dollars have been spent on this long simmering saga, and to no avail," he said. "I declined to answer the questions under the rights and privileges afforded to every citizen under the United States Constitution."

Ms James' office confirmed that the interview took place on Wednesday and that "Mr Trump invoked his Fifth Amendment right against self-incrimination".

"Attorney General James will pursue the facts and the law wherever they may lead," the statement added. "Our investigation continues."

His deposition comes just days after the FBI executed an unprecedented search warrant at his Florida estate, Mar-a-Lago, as part of a separate investigation that is reportedly linked to his handling of classified material.

While the attorney general's investigation is a civil one, a parallel investigation is being carried out by the Manhattan District Attorney's office which could result in criminal charges.

Legal analysts suggest Mr Trump may have declined to answer questions on Wednesday because his answers could have been used against him in that criminal investigation. The former president invoked the Fifth Amendment, which protects people from being compelled to be a witness against themselves in a criminal case.