Ulster Bank is to remain a key part of parent company Royal Bank of Scotland (RBS), the bank has said.

In a statement released with results for the third quarter, RBS said it was holding on to the Irish operation and with appropriate investment it will deliver good returns.

"Ulster Bank remains a core part of RBS, offering a good strategic fit with our focused retail and commercial banking strategy," RBS said.

"We have a good market position and believe that Ulster Bank can deliver attractive returns, with appropriate investment."

RBS said operating profit at Ulster Bank increased by £336 million (427 million euro) to £394 million (485 million euro) in the three months to the end of September.

It credited its improved trading to a number of factors including economic growth, the bounce in the property market, lower unemployment, proactive debt management and stable restructuring costs.

Ulster Bank also noted an increase in demand for new lending from personal and business customers this year.

Ross McEwan, RBS chief executive, said: "UK and Ireland are showing signs of growth, and impairment trends are significantly better than we had anticipated at the start of the year.

"We have confirmed today that Ulster Bank remains a core part of our bank.

"We have a good market position and believe that, with investment, Ulster Bank can deliver attractive shareholder returns in the future.

"But we know we still have a long list of conduct and litigation issues to deal with and much, much more to do to restore our customers' trust in us."

On the IT problems that severely disrupted business in 2012, Ulster Bank said it expects to begin settlement discussions with the Central Bank of Ireland (CBI) before the end of the year.

The results were released as part of trading statements from RBS, which is 80% owned by the UK taxpayer.

It said profits for the third quarter were up to £1.27 billion, compared with a loss of £634 million in the same period last year.

It is the first time the bank has reported a profit for three quarters in a row since the financial crisis in which the bank nearly collapsed.

As part of the statement it is setting aside £400 million to settle foreign exchange rigging allegations.