"allegation regarding" is a correct and usable phrase in written English.
You can use it when you want to describe something that someone is claiming or accusing. For example: The senator denied the allegation regarding his involvement in the scandal.
Speaking by phone, I explained that two sources had told me that she had a serious allegation regarding the producer.
"After reviewing an allegation regarding voting on the people's choice award, our finding is the award should stand," she said.
Blasphemy is "abhorrent and immoral", the judgment said, "but at the same time a false allegation regarding commission of such an offence is equally detestable besides being culpable".
"Any time there is an allegation regarding abuse of the privacy and civil liberties of Americans it is a very serious matter," he said.
"In fact, when I first learned of this wrong allegation regarding his appearance, I called the commission and made arrangements for his appearance on a mutually convenient date.
Three days later, Snapchat finally responded publicly by posting a brief, vague note on its blog about "an allegation regarding a possible attack by which one could compile a database of Snapchat usernames and phone numbers".
Mr Johnson said allegations regarding one MI5 officer alleged to have known of Mr Mohamed's ill treatment, referred to as Witness B, had been referred by the Government to the Attorney General.
There had been an "over-cautious approach" in the past to allegations regarding Savile.
The GLA says it has now passed on these allegations regarding Rosegar to its "intelligence team".
A Glencore spokesman said they had refuted allegations regarding human rights and environmental abuses many times.
The case concerned allegations regarding the "governmental and administrative functions" of Derbyshire council.
