A knife-wielding man who caused the closure of the Clem7 in Queensland for almost seven hours on Thursday has been charged with a string of offences.

Police said the 40-year-old man demanded staff members at a cafe on Baines Street in East Brisbane hand over knives before taking two blades from a bench and leaving the premises about 6.50am.

Police negotiated with the armed man, who was on top of the Clem7 tunnel entrance in Kangaroo Point. Credit:Nine News

A short time later, police claimed the man returned and threatened a customer with the knives before forcing his way back into the cafe and making further threats to staff.

Cafe employee Michelle Curtis told Nine News she and two other staff members climbed over the counter to escape the danger.