"There was definitely someone in the apartment block filming but it might have been a Japanese fan," the Australian said.
Despite the training pitches being surrounded by high sheeting and security guards patrolling to prevent unauthorised filming, Jones said he didn't mind if the session had been recorded.
"I don't care, that's part of the deal. That's the fun of the World Cup," he said.
Jones said he used to do the same thing but hadn't done so since 2001. "You just don’t need to do it any more, you can see everything," he said. "You can watch everyone’s training on YouTube. There's no value in doing that sort of thing, absolutely zero."
Saturday's semi-final opponents New Zealand and tournament officials are unlikely to take much notice of Jones's latest claims, particularly as he made an almost word-for-word accusation ahead of the Six Nations in January.
"I can guarantee (Wales coach) Warren Gatland sends someone when we have an open session," he said at the time.
He also warned then that opportunities for spying at the World Cup would be rife because "a number of grounds in Japan are surrounded by office buildings".