A jogger has caused a major security scare in the UK after he nearly ran into British Prime Minister David Cameron as he left a press conference in Leeds.

Mr Cameron was leaving the Leeds Civic Hall on Monday when local man Dean Farley, aged 28, ran across the street towards him.

Police stepped in to bundle him to the ground as Mr Cameron got into a waiting vehicle.

Mr Cameron's security team grab the man as he runs towards the PM. (BBC) (BBC)

Mr Farley posted on Facebook that he only "brushed into" Mr Cameron and claimed he was a victim of "assault".

"So im all over the news as 'the protester that attacked david cameron in leeds' yeah if you call brushing into someone while running then getting assaulted by half a dozen coppers in suits attacking," he wrote.

Chief Inspector Derek Hughes of West Yorkshire Police said the 28-year-old was briefly arrested.

"No threats were made, and after the man's details were checked he was de-arrested and allowed on his way."

The incident has raised questions over how a member of the public was able to get so close to Mr Cameron without being stopped by security.

"It is a serious breach of security and I wouldn't be surprised if people on the team are transferred as a result," Andy Redhead, a consultant with security firm FSI Worldwide, told the UK Telegraph .

Dean Balboa Farley. (Facebook)

"It's a really appalling incident - not good at all.

"Fortunately the man had no acid, no knife, no firearm, and there was no threat.

"Looking at the footage, one of the team seems distracted by a female who is a legitimate member of the party, a second member is looking in completely the wrong direction and a third member is too far away to close the whole thing down.

"The whole team has let each other down and I'm sure serious questions are being asked."

Conservative MP Mark Pritchard called for an inquiry into the incident, asking "what if the protester had been carrying a knife?"