Aberavon MP Stephen Kinnock has denied concealing details about his daughter's private education when seeking selection for the safe Labour seat.
Mr Kinnock's eldest daughter Johanna attended Atlantic College, near Llantwit Major, in the Vale of Glamorgan from 2013 to 2015.
He said her study was "partly funded by a standard Danish state scholarship".
He was responding to an accusation that he failed to reveal the matter when seeking selection, something he denies.
During Labour's selection process for the Aberavon seat in 2014 Mr Kinnock was asked about his daughter's education in Denmark, where his family were based and where his wife Helle Thorning-Schmidt was prime minister at the time.
He said to Wales Online at the time that Johanna went to Ingrid Jespersen School (IJS) in Copenhagen from 2010 to 2012 - where Mr Kinnock has said parents were "obliged" to make a monthly contribution of £160.
But a blog, "Jac o' The North", has accused Mr Kinnock of failing to reveal in 2014 that his daughter was at Atlantic College.
Mr Kinnock said he was responding at the time to questions about the school in Denmark.
He says he has "always been open" about Johanna's education in Wales and said in a statement on his website that her time at Atlantic College was "partly funded by a standard Danish state scholarship for students studying abroad".
Annual fees at the college are currently around £28,600.
In the statement Mr Kinnock said: "Shortly before the late March 2014 hustings for the Aberavon Constituency Labour Party MP selection I was asked to clarify whether or not Johanna had attended a private school in Copenhagen. I explained that she had spent two years at IJS.
"The author of this blog claims that the facts of the matter were somehow being concealed; they were not.
"I was being asked about, and responding to, questions about, the nature of Johanna's education in Denmark, and not about the nature of her education at [Atlantic College]."
A source with knowledge of the Aberavon selection contest told BBC Wales Mr Kinnock would not have won the selection if it had been known at the time that Johanna was at Atlantic College.
He said: "It would have changed people's perception, it would have made the difference.
"There was only one vote in it."