The man claimed to be a diplomat when he was stopped by security officers, a court was told
Peter Herod, 61, was heading for a meeting with Labour MP Hazel Blears and Baroness Scotland when he was stopped and searched.
He was caught with the lock-knife, a court heard.
When security officers stopped him, he claimed he had diplomatic immunity, it is alleged.
It is understood the man was trying to get to the UK launch of the Brussels declaration pledge to peace, held at the Palace of Westminster on June 17 last year.
Wearing a grey suit and an orange patterned tie at London's Southwark Crown Court, Herod denied having an article with a blade or point.
Herod, of Burr Street in Didcot, Oxfordshire, also denied possessing an article for use in fraud.
His case was adjourned for the prosecution to check with government officials if Herod had diplomatic immunity.
Judge Alistair McCreath said: "They have a list of people who have diplomatic immunity.
"If you are not on it, end of."
The case was adjourned until April 9 at Southwark Crown Court.