Virgin said the new trains had led to a 40% rise in passenger numbers

In one, the company claimed the introduction of new trains had "dramatically reduced journey times".

But a member of the public who contacted the Advertising Standards Authority (ASA) complained that some journey times between Penzance and Birmingham had actually increased.

The second advertisement, which appeared in a train timetable, said "all trains in this timetable, unless otherwise shown, offer a range of enhanced on board services including at-seat audio entertainment" and "power-points near every seat to charge laptops and mobiles".

The claim was dismissed by one passenger who contacted the ASA, which said it believed around 30% of services through Bristol used old trains without the advertised features.

On the first complaint Virgin Rail said the claim had referred to the "overall impact the new trains would have on the service, not on specific routes" but conceded some journey times had not been reduced.

Defending the second advertisement, the company claimed the new trains had led to a 40% rise in passenger numbers.

It also said older trains had been brought into service to offer more capacity and reduce overcrowding.

After an investigation the ASA upheld both complaints, saying the claims were "likely to mislead".