flat out deny
flatly deny

The senator's office flatly denies that the city changed its mind.

Those two flatly denied ever having seen him anywhere before.

He claims to have looked into this already, and says that the Order flatly denies any knowledge.

He flatly denied that Wallace had been at the hotel.

He flatly denied the accusations against him in an interview only days before.

And anyway, I couldn't bring myself to flatly deny the monster.

He was on the witness stand for about a minute, and flatly denied any role in the killing.

The president of the security company flatly denied that anyone was mistreated.

Yet these same leaders flatly deny any affiliation with the killers.

The government has flatly denied the rumor and all political parties have said there is no truth in it.