Media regulator Ofcom said it has "serious concerns" about a growing number of complaints about call-TV quiz services after it found two Quiz Call programmes guilty of breaching the broadcasting code.
An episode of Quiz Call on Channel Five in September last year was censured after a presenter described a "difficult mathematics" game as "easy".
Ofcom ruled that this would have affected whether people chose to play and ruled the episode was not conducted fairly.
Five said the use of the word "easy" in describing the quiz was "not ideal" and said that it would be holding a seminar with the programme's staff to ensure they understand the detail of the broadcasting code.
Ofcom also ruled against the Word Association game on the Quiz Call channel, which was owned by Channel 4 at the time of the complaint in September.
Two viewers complained about the quiz in which they were asked to name "things in Australia", with one of the answers flagged up by the presenter as "Alice something" with the word "Alice" followed by seven asterisks on the screen.
However, the answer turned out to be "Alice Springs Camel Cup" which no viewer got correct.
Ofcom ruled that the correct answer was "almost impossible" for callers to have considered.
Channel 4 admitted that the clue on screen "may have suggested that a seven letter answer was required" and apologised for the error.
Ofcom said today that it had "serious concerns" about a "growing trend" in complaints relating to the conduct of some quiz TV competitions.
The regulator, which last week confirmed it would launch an official investigation into the quiz TV sector, told broadcasters it would consider the imposition of "statutory sanctions" against those who "seriously, deliberately or repeatedly" breach the code.