They may have a growing number of fans, but online video on demand services are not eating into viewer figures for traditional TV.

According to Thinkbox, which compiled data from ratings body Barb, broadband video catch-up services such as the BBC iPlayer are not replacing traditional TV viewing, but complementing it.

The results revealed that UK viewers watched an average of 3.77 hours of broadcast TV a day in the first half of the year, a 2% increase on the five-year average for the period.

"That both broadcast and online TV platforms are growing simultaneously underlines how they fulfil different needs for viewers and that they can co-exist and indeed promote each other," said Thinkbox.

Thinkbox in fact claims that commercial broadcast TV had a "record breaking" first six months of the year.

And this is good news for advertisers.

Total commercial impacts - the viewing of one ad, one time, by one person - was up 6% year-on-year.

And commercial broadcast viewing is "performing very strongly", up 4% on the same period last year, fuelled by factors including poor weather and the increase in digital TV penetration.

"This is a shaft of very bright light that cuts through any economic gloom," said Tess Alps, chief executive of Thinkbox.

"Advertisers should be taking advantage of a medium that offers proven effectiveness, increasing value and is growing," she added.

But the second half of the year may not be quite so good.

Market leader ITV last week predicting it was heading for a 20% year-on-year dip in advertising revenue in September.