As dramatic setpieces go, Oscar-winner Kevin Spacey's five-minute apologia on the BBC's Today programme would not rank among his finest.

In an attempt to calm a media storm that threatens to overshadow this week's relaunch of the Old Vic theatre, where he is artistic director, the actor gave an intriguing explanation for the riddlesome events that landed him on yesterday's front pages.

Spacey, 44, had reportedly been "brutally mugged" as he took his dog for a walk in a south London park at 4.30am on Saturday. The star, who won Oscars for The Usual Suspects and American Beauty, then contacted police some hours later and changed his story, according to the Daily Mirror.

In an effort to "come clean" and explain the mystery of the walk-in-the-park incident, Spacey took the unusual step of offering an apology during a Today programme slot which had been reserved for his much-anticipated revival plans for the Old Vic.

"I just want to apologise to the police, and any readers and anyone who picks up this story thinking it is actually true," said the star as he tried to explain himself.

"I am very well and I am also glad to set the record straight here and also to apologise, because there is no reason that this article would have been written if it hadn't been for me and what I initially said to the police.

"What actually happened is, I fell for a con. And I was, I think, incredibly embarrassed by it. Some sob story about somebody needing to call their mother.

"It was such a good con, that I actually dialled the number myself and when somebody answered I then finally handed [over] my phone. And this kid took off and I was so upset I ran after him.

"I tripped up over my dog, and I ended up falling on to the street and hitting myself in the head.

"And now I'm bleeding relatively profusely, I'm extremely upset, I feel like the biggest fool that has ever lived.

"I march over to the police station and I say I got mugged. And I'm thinking they are going to run out and find this kid a block later. Of course, they take me to the hospital, and they were very kind."

The actor said he had gone back to the police station the next morning to confess he had fibbed. "It just wasn't on for me to not come clean about my own level of embarrassment," he added.

Asked what he was doing in the park at such an odd hour in the first place, he replied: "You know walking your dog in the park is a perfectly normal thing to do ... My doggy had to go!"

His confession drew mixed reactions in the world of publicity. While PR expert Mark Borkowski said Spacey showed "refreshing honesty" and was "very plausible", Max Clifford branded the public confession a mistake.

"From a PR point of view the statement doesn't sound very satisfactory - it sounds like nonsense. If it was intended to to limit any potential damage, I think the opposite has been achieved. This statement will add to the speculation rather than diminish it."