Channel 4's E4 and FilmFour will stop broadcasting on the defunct ITV Digital platform on Friday.

The channels negotiated an extension with ITV Digital's administrators after the failed digital platform stopped broadcasting on 1 May.

But the pay-TV channel can no longer recoup any revenue by broadcasting via ITV Digital and so it is not in the company's interests to continue transmissions.

The end of E4's broadcasts on ITV Digital will rob it of 10% of its potential audience on the same day that Big Brother 3 launches.

The latest version of the reality show will have E4 at the centre of the phenomenon with round-the-clock coverage.

E4 will feature Little Brother

FilmFour has carved out a niche by screening classic and cult films for a monthly subscription, with E4 showing many Channel 4 programmes like Friends and ER first.

A spokesman for Channel 4 said the extra three weeks of broadcast had been a "bonus" for ITV Digital customers.

"For three weeks it has been a bonus for people who wouldn't necessarily have expected any of the channels they had on their package."

The bidding process for the ITV Digital's three broadcast licences has now started.

Extra bandwidth

The terrestrial channels are in the process of building a consortium to acquire the licences.

They want digital broadcast of free-to-air terrestrial channels to be improved by using the extra bandwidth now available through the licences.

But it will be some time before the shape of the new regime for digital terrestrial television becomes clear.

And as E4 and FilmFour are not free-to-air channels, they may remain unavailable.