Two of the BBC's most senior managers were accused yesterday of being "dangerously out of touch" with the way the corporation's programmes are made as they received a grilling from MPs over the TV phone-in scandal.

Also appearing before the Commons media committee, Michael Grade, ITV's executive chairman, announced his company was adopting a "zero tolerance" policy towards anyone found deceiving viewers.

In a parallel development, Channels 4 and five announced plans to "safeguard viewer trust" by co-producing a handbook on best practice for all independent producers.

With Mark Thompson, the BBC's director general, on a family holiday, it fell to Mark Byford, his deputy, and Caroline Thomson, the corporation's chief operating officer, to be asked to explain how viewers were deceived in a string of shows, including Children In Need and Comic Relief.

Pledging to restore public confidence, Mr Byford described the deceptions as totally unacceptable and said honesty lay at the heart of the relationship between the BBC and its viewers.

He described how he was stunned by the six deceptions revealed last week, which began when Blue Peter was found to have faked a competition winner.

However, Mr Byford admitted: "We can't be 100% certain we have captured everything. Some investigations are still going on. We may get other cases. I hope, obviously, we don't but I wouldn't rule it out."

He revealed three senior editorial staff had been suspended but dodged questions about whether he or Mr Thompson should resign.

Philip Davies, the Conservative MP for Shipley in Yorkshire, asked him: "What would it take for you and Mark Thompson to decide your position is no longer tenable?"

Mr Byford replied: "Our position was made perfectly clear by the BBC Trust. They judged rightly this is very serious and that our task is to make it clear to every member of staff that works for the BBC that we won't tolerate it. That is on our shoulders."

On the controversy over a documentary on the Queen, which wrongly implied she had stormed out of a photoshoot, Mr Byford conceded there had been a "delay" between when the BBC found out about the deception and making it public. "There were reasons for that delay but that will come out in the investigation," he said.

Ms Thomson said the corporation had been "surprised, stunned and shocked" by the string of deceptions, adding: "It's a sad day for us."

In his evidence, Mr Grade revealed ITV had suspended its commissions from RDF, the company which made the trailer for the BBC's royal documentary, pending the outcome of an inquiry into why it was edited in a deceptive way.

He told MPs if any production company were "found to have deceived or lied to viewers, we won't do business with them; it will be zero tolerance," adding: "If you want to work with me: one strike and you're out."

On the back of the row over the Queen documentary, Channel 4 announced new clearance procedures for promotional materials while five said it was reviewing its relationships with independent TV companies as well as its contracts and processes to "ensure viewers can have total faith in the broadcaster".

Meanwhile, broadcasting regulator Ofcom unveiled new rules to protect viewers who take part in phone-ins. Launching a consultation, it wants broadcasters to be made responsible for consumer protection and for compliance with premium-rate services rules as a condition of their licences.

Its plans follow the release last week of a scathing report into the way TV broadcasters operate their premium rate phone services.