Coulson was accused by prosecutors of conspiring to obtain private information about Britain's royal family, while Brooks was charged over payments of 100,000 pounds to a civil servant from the Ministry of Defence to garner details for news stories.
Cameron received a double blow to his reputation after the Court decided to charge Brooks and Coulson, whom Cameron had been forced to defend his hiring since a phone-hacking scandal exploded last year at the now-closed News of the World .
Critics believe Cameron - who meets Queen Elizabeth once a week - ignored warnings about Coulson's reputation and appointed him to shape his media strategy to connect better with ordinary voters.
The charge against Brooks, whose friendly texts and emails to Cameron were laid bare at a public inquiry into press standards, compounds the embarrassment for him.
Asked if hiring Coulson and being so close to Brooks reflected badly on his judgment, Cameron said: "I have made it clear (my) regret on many occasions on this issue.
"I have also said very clearly that we should allow the police and prosecuting authorities to follow the evidence wherever it leads, I think that is very important," he told reporters during a visit to Northern Ireland.
Like Coulson, Brooks has also been charged with attempts to pervert the course of justice.
British Prime Minister David Cameron has been faced with fresh embarrassment after a court charged his former media chief of offences linked to bribery.
On Tuesday, Westminster Magistrates Court charged former media chief Andy Coulson and the former boss of Rupert Murdoch's British newspaper business Rebekah Brooks conspiring to pay officials illegally to obtain information for new stories.
At the time, Brooks and Coulson were editors of the Murdoch-owned News of the World Sunday tabloid and its sister daily paper the