Labour MP John Mann said it was extraordinary that Downing Street did not make any public announcement after the resignation and arrest of former government policy adviser Patrick Rock.
"This is a man in the heart of 10 Downing Street, in the heart of government, couldn't be closer to power, he is part of power, and the fact that they've withheld that information for three weeks is all in all unacceptable," he said.
Explaining why Downing Street didn't make a statement at the time of Mr Rock's resignation, David Cameron said: "I I don't think it would be right to preemptively brief out a criminal investigation and that's why we did not do that."
"But as soon as questions were asked, as questions would inevitably be asked, we have given very full and straightforward answers," the Prime Minister added.
More top news
Paranoid schizophrenic Jeffrey Barry stabbed Kamil Ahmad before removing his penis in the attack at his flat in Bristol last year.
The latest addition to the royal family will be a younger brother or sister for Prince George and Princess Charlotte.
The Duchess of Cambridge, who is pregnant with the couple’s third child, will stay at home while William visits Finland for a two day tour.