The adverts are running in Truro and two other UK locations

The Royal Cornwall Hospitals NHS Trust claims Norwich Union's adverts for private healthcare insurance quote incorrect waiting time figures.

But the insurers said they used the "latest available waiting list data" for the campaign.

The adverts are running as a pilot in Truro and two other areas.

We are simply putting the facts to people and offering a solution to the problem should they be interested Lorna Wiltshire, Norwich Union

One of Norwich Union's adverts quotes a waiting time for cataract operations of 399 days, a figure which the hospital says is exaggerated by more than 100 days.

Another advert is a mock travel information board with the headline: "Delays possible at Royal Cornwall Hospital. Take alternative route".

In a statement, the Trust said: "The Norwich Union is undermining the excellent work that we are all doing at the Royal Cornwall Hospitals Trust and in the health and social care community to reduce waiting times.

"It will also cause great concern for many of the elderly and vulnerable who can least afford to pay for their healthcare.

"The facts are that waiting times are coming down fast and we do not think that this kind of aggressive and negative marketing is the right way to promote their services."

Apology offered

Norwich Union said any offence caused by the campaign, which started on 4 October , was unintentional and apologised for any upset caused.

Lorna Wiltshire, Norwich Union media relations manager, added: "Our customers tell us that having to wait for treatment on the NHS is still of concern to them.

"We are simply putting the facts to people and offering a solution to the problem should they be interested."

She said the data used in the advertisements was provided by an independent organisation providing UK healthcare information, and dated back to 2003.