A federal grand jury in Maryland has indicted John Bolton, United States President Donald Trump’s former national security adviser, over his handling of classified documents, charging him with retaining and transmitting national defence information.

The indictment, filed in federal court in Maryland on Thursday, charges Bolton with eight counts of transmission of national defence information and 10 counts of retention of national defence information, all in violation of the Espionage Act.

Each count is punishable by up to 10 years in prison if Bolton is convicted, but any sentence would be determined by a judge based on a range of factors.

Bolton’s lawyer Abbe Lowell said in a statement that his client “did not unlawfully share or store any information.”

Bolton served as US ambassador to the United Nations as well as White House national security adviser during Trump’s first term before emerging as one of the president’s most vocal critics. He described Trump as unfit to be president in a memoir he released last year.