 Staff are picketing outside ITV's London Television Centre |
Ant and Dec's Saturday Night Takeaway is among ITV programmes being disrupted by strike action. The 36-hour walk-out by 700 production staff across the UK is over a rejected 3.3% pay rise offer.
Ant and Dec's hit show was "recorded as live" on Thursday, while two editions of music show Hit Me Baby One More Time are being shot at the BBC's studios.
ITV said This Morning had been cancelled to make way for live coverage of Pope John Paul II's funeral.
Picket lines
Broadcasting unions Bectu and Amicus earlier claimed that Friday's edition of the daytime show would have to be shelved due to industrial action.
 | Our members have effectively suffered year on year pay cuts while ITV executives and shareholders have been generously rewarded |
Staff in London, Leeds and Manchester have said they will remain on strike from 0700 BST on Friday until 1900 BST on Saturday, manning picket lines outside ITV studios.
Bectu members in Nottingham, Birmingham, Norwich and at ITV's southern transmission centre in London are also taking part in a two-hour stoppage from 1200 to 1400 BST on Friday.
Unions also claim the stoppages will disrupt filming schedules of popular ITV dramas such as Coronation Street, Emmerdale and Heartbeat.
 Ant and Dec's Saturday Night Takeaway usually goes out live |
But an ITV spokesman said: "Our entertainment shows will go out as planned on Saturday and we do not foresee a delay in delivering drama serial programming on schedule."
Music programme Hit Me Baby One More Time has moved production to BBC's Television Centre and will go out live as planned on Saturday, while Parkinson's chat show was pre-recorded on Thursday as usual.
"The delivery of episodes of Coronation Street, Emmerdale and Heartbeat will not be affected," said an ITV spokesman.
The action comes after ITV announced �340m pre-tax profits and a �1.9m pay package for chief executive Charles Allen.
Further action
"Our members have effectively suffered year on year pay cuts while ITV executives and shareholders have been generously rewarded," said Mike Smallwood, Amicus' national officer for the broadcast industry.
ITV has said it believed its pay offer was fair when combined with the promise of a minimum salary of �13,500 and an extra day's holiday to celebrate the network's 50th anniversary.
Both unions will be taking further action in London, starting again at 0700 BST on Friday 15 April.