North Wales Police is considering a complaint made against Prime Minister Tony Blair over allegedly using a swear word in relation to Welsh people.
Mr Blair is accused of making the remarks in 1999
According to ex-Downing Street press officer Lance Price's diaries, Mr Blair used the insult in 1999.
Mr Price said Mr Blair repeatedly swore while watching disappointing results in that year's Welsh assembly election.
But he said the prime minister was referring to the Labour Party in Wales and not at Welsh people in general.
North Wales Police said a complaint had been made and they were seeking Crown Prosecution Service (CPS) advice.
The police would not confirm who had made the complaint, but the Welsh language pressure group Cymuned has claimed it asked for the investigation.
The CPS has to determine whether an investigation would be in the public interest and if there was a reasonable chance of conviction before deciding whether to proceed.
A North Wales Police spokesman said: "A complaint has been received and is being reviewed.
"We will be seeking the advice of the CPS in relation to the content of the statement of complaint."
According to Mr Price's diaries, Mr Blair made the insult as disappointing results for Labour from the 1999 Welsh assembly elections came in.
He is alleged to have said "Fucking Welsh" repeatedly.
The claim was made in a draft version of the diaries, but toned down in the final published version to read: "TB f-ing and blinding about the whole thing."
Plaid Cymru's social justice spokesperson Leanne Wood made a complaint to the parliamentary standards commissioner when reports of the comments first emerged.
She said: "I initially felt that Tony Blair's comments were so offensive that I wanted to complain to the police.
"Instead I decided to refer the matter to the standards commissioner.
"If North Wales Police require any evidence from me, I would be more than happy to provide it. Tony Blair's comments are extremely offensive to the Welsh people - he should make a public apology."
Mr Price, whose diaries have sparked the row, denied that the prime minister has a "downer" on the Welsh.
Mr Price told BBC Wales that Mr Blair was disappointed with the results and the way the election was conducted.
He added: "My assessment now is that he was more likely to have been talking about the Wales Labour Party than the people of Wales in their entirety.
"I wrote he was effing and blinding about the Welsh, but my assessment of it looking back is that he was talking about the Welsh party rather than Welsh people having made a democratic choice.
"He didn't have a general downer on the Welsh, I have never heard him express any malign sentiments about the Welsh or criticise the Welsh in general."
Mr Price added that any investigation by North Wales Police would not be worthwhile.
"I sincerely hope they won't go down the route they did in the case of Anne Robinson, when a lot of money was wasted," he said. "If the phrase has caused offence in Wales, which I'm sure it has, I don't see how that would be helped by a police investigation that will probably go nowhere."
Earlier this month, it was revealed that North Wales Police spent nearly £4,000 investigating comments about Welsh people made by television presenter Anne Robinson when she appeared on a BBC chat show four years ago.