poricati

1. to deny
   Ministar poriče sve optužbe. — The minister denies all the accusations.
   Niko ne poriče da je situacija teška. — Nobody denies that the situation is difficult.
2. (guilt, responsibility) to deny; to disavow
   Optuženi i dalje poriče krivicu. — The defendant still denies his guilt.

The perfective is poreći; common in ne može se poreći da… 'it can't be denied that…'.