A complaint about alleged anti-Welsh swearing by Prime Minister Tony Blair seems unlikely to go any further.
The claims focus on Mr Blair's response to the 1999 election
A preliminary North Wales Police inquiry shows no grounds for more investigation, says the Crown Prosecution Service (CPS).
Former Downing Street spin doctor Lance Price claimed in his diaries that Mr Blair swore over bad Labour results in the 1999 Welsh assembly election.
Police said they would "ensure that every aspect is properly investigated".
It has not been revealed who made the complaint, although the Welsh language pressure group Cymuned has said it asked for an investigation.
The CPS said on Monday that the chief crown prosecutor for north Wales had advised "that the preliminary investigation has not revealed any grounds to merit further investigation."
But police said there were "a number of issues associated with the alleged comments" and it would "continue to work with the CPS to ensure that every aspect is properly investigated."
Clwyd West Conservative MP David Jones said he found it incredible that police were planning to continue the investigation.
Mr Jones said: "The whole of north Wales knows it's a nonsense. That's the view of the man in the street and also the view of the CPS."
In a draft version of his book, Mr Price claimed that Mr Blair said "f*****g Welsh" repeatedly as the election results arrived, and Labour won only 28 of the assembly's 60 seats.
These words were toned down for the published version of the diaries.
However, Mr Price told BBC Wales last month that he did not believe the prime minister had anything against the people of Wales, but instead was talking about the Wales Labour Party.
A couple from Anglesey who protested to Mr Blair last month received a reply from Downing Street which said he had no recollection of the comments, and he took great pride in being prime minister of the United Kingdom.
The reply went on: "He is particularly proud that it was this government which gives Wales the opportunity of its own National Assembly and devolved administration."