WASHINGTON, June 14 (Xinhua) -- U.S. President Donald Trump was enraged on Thursday after his charitable foundation was accused of illegal conduct.

New York Attorney General Barbara Underwood sued the Donald J. Trump Foundation along with its directors -- the president and three of his children -- in State Supreme Court in Manhattan earlier in the day.

The lawsuit accused the foundation of illegally coordinating with Trump's presidential campaign, "repeated and willful self-dealing transactions" and failing to follow related laws for over a decade.

The complaint alleges that the Trump Foundation engaged in repeated and willful self-dealing transactions to benefit Trump's personal and business interests.

Underwood asked a court to dissolve the foundation and order it to pay a fine of 2.8 million U.S. dollars.

Trump immediately attacked the lawsuit, calling it in a Twitter post as a "ridiculous case," claiming that he would not settle it.

Three of Trump's children, Donald Trump Jr., Ivanka Trump and Eric Trump, were also named as defendants in the lawsuit, adding to legal challenges facing the president.

The foundation, based in New York, was established by Trump in 1988.