State-backed Royal Bank of Scotland has come under fire once again - this time for making "misleading" promises to be the "last bank in town".

RBS, which is 83% owned by the taxpayer and is being propped up with billions of pounds of public money, was rapped by the advertising watchdog for the claims made in two television commercials which have now been banned.

It follows a torrid few weeks for the bank in which boss Stephen Hester was forced to give up a £963,000 share bonus amid huge political pressure and his predecessor, Fred Goodwin, was stripped of his knighthood for his role in leading the bank to the brink of collapse.

The Advertising Standards Authority (ASA) was brought in after several complainants voiced objection to the two advertisements screened in June.

The first, for NatWest, showed staff outside a branch on a deserted coastal road claiming that NatWest would "continue to provide banking services wherever we're the last bank in town". The second commercial, for RBS, featured different characters and settings with a similar script.

But both were challenged by viewers who identified Farsley, in Yorkshire, as a location where a branch of NatWest had been closed - despite being the last bank in the area. The ASA later established that RBS had also closed a premises in the Scottish town of Bettyhill, replacing it with a mobile bank.

Responding to the NatWest advert, it said: "Because (the advertisement) stated that Natwest would continue to provide banking services if it was the last in town and because we understood that there was a town in which they had not done so, we concluded that the claim was misleading."

It came to a similar conclusion in relation to the second commercial. An RBS spokesman said the bank disagreed with the watchdog's decision.

In a response to the ASA, RBS defended the closure of the Farsley premises and insisted it had never promised to keep all branches open. Meanwhile, it claimed to have improved services in Bettyhill, where it replaced "two desks in a community centre" with the mobile bank.

"While we disagree with the ASA's decision, we welcome their offer to work more closely with them in future," a spokesman said.