The TV phone quiz scandal deepened yesterday when broadcaster Five admitted some of its competition winners were faked.
Daily lunchtime show Brainteaser asked viewers to solve a word puzzle within five minutes.
But when the audience failed to get the answer winners listed on screen were simply made up.
On one occasion a member of the crew went on air posing as a "winning contestant".
The quiz is produced by Cheetah Television, a subsidiary of Big Brother maker Endemol UK.
The con came to light after Five, which knew nothing of the scam, began a review of its premium rate telephone services.
Cheetah contacted Five yesterday to warn them "irregularities" had been found.
As a result Five announced yesterday that it was suspending all programming involving premium rate telephone services.
Five chief executive Jane Lighting said: "We are shocked and disappointed and wish to apologise unreservedly to our viewers.
"The production company involved has failed to meet the high standards we demand."
The bogus names were used on five occasions between January and Tuesday this week, the internal review found.
Viewers were charged 75p per call to enter the "quickfire" element of the quiz, in which they were given approximately five minutes to solve a word jumble puzzle.
Five said: "When the five minute window and the phone lines had closed, Cheetah Television, working through a list of callers supplied by the phone service provider, were unable to find a caller with the correct answer before the winner was due to be announced on air. Instead of informing viewers that no winning caller had been found in the time period available, the production company put fictional names on screen as "winners". On one occasion a member of the production team went on air as a "winning" contestant.
"Five is ascertaining how many callers have been affected on these five occasions and will be giving them a full refund of the cost of the call."
Endemol UK said it apologised unreservedly: "We fully support Five's decision to take Brainteaser off air."
Five's decision to suspend its programmes follows the announcement of an ITV review into its own premium-rate phone-ins, ordered by new chairman Michael Grade.
The quiz channel ITV Play, which takes in an estimated £18m a year, has been axed until further notice.
Premium rate services regulator Icstis confirmed yesterday it was investigating six shows: Channel 4's Richard and Judy, the BBC's Saturday Kitchen, and ITV entertainment series X Factor, Ant and Dec's Saturday Night Takeaway, Soapstar Superstar and I'm A Celebrity.
Icstis chairman Sir Alistair Graham said broadcasters had got themselves into a "pretty grim mess".
Icstis could call in the police if its investigation reveals evidence of criminal activity.
Icstis also has the power to impose heavy fines for wrong-doing.
It yesterday announced the introduction of a licensing regime for all premium rate service providers.