The New York state attorney general has filed a lawsuit against former US President Donald Trump, members of his family and senior managers of the Trump Organization after years of investigation into the group's financial practices.

Letitia James says Trump falsely inflated his net worth by billions of dollars "to unjustly enrich himself and cheat the system."

The lawsuit alleges Trump did this with the help of three of his children -- Donald Jr., Ivanka, and Eric -- as well as other executives in the organization he led.

The suit says they conspired to make it easier for them to obtain loans, get insurance, and gain tax benefits.

James is seeking penalties of 250 million dollars. She also wants to bar the Trumps from conducting business anywhere in the state.

The former president has accused her repeatedly of being politically motivated, calling the investigation a "witch hunt."