A man has admitted sending hoax white powder to Norwich North MP Chloe Smith.

Richard Hayes, 40, of no fixed abode, was arrested in Barnstaple, Devon, on July 18 by counter-terrorism officers.

He appeared via video link at Exeter Crown Court on Thursday and admitted 16 charges of making a noxious substance hoax, contrary to section 114 of the Anti-Terrorism, Crime and Security Act 2001.

Charges state that Hayes sent white powder and packages marked "anthrax" from Exeter to constituency offices of MPs and local councillors, including Conservative Ms Smith, between May 2011 and April 2014.

Judge Peter Johnson adjourned the case for reports to be carried out but warned Hayes that he faces "a lengthy custodial sentence" when sentenced in November.

Ms Smith's office received a brown envelope in August 2013 which contained a white substance, later found to be a harmless protein powder.

It was opened by her parliamentary assistant and the powder was hidden in what looked like a folded up piece of notepaper.

At the time the assistant said: "I got white powder all over my desk and hands and trousers.

"I had a brief look to see if there was anything written on the paper and also saw there was a postmark from Exeter.

"I was advised not to eat or drink or visit the bathroom. It was uncomfortable.

"I thought it was probably nothing. They told us that 99pc of the time it's a hoax, so I wasn't frightened in that respect. But I did feel nervous at times."

Ms Smith said: "It is my staff who bear the brunt of this. It is not fair. As an MP you expect to be able to get on with your job of serving your constituents without coming under physical attack, which is what letters such as these are, even if they are hoaxes.

"It is not fair on the staff of MPs who help open the post to be attacked in this way."

Following the letters being received parliament's Serjeant at Arms issued advice to other politicians about how to deal with such attacks and warned politicians to be on the lookout.