Ulster Bank has reported an operating profit of £131m (€178m) for the first half of its financial year, compared to £55m (€67m) in the same period of last year.
Of that £80m (€109m) was earned in the second quarter alone – almost double the operating profit recorded in the April to June period of 2014.
This was despite a fall in the bank’s revenue, with net interest income falling 18% to £265m (€362m).
Ulster Bank said that while its results were affected by the weak euro it saw higher profit, lower costs and lower impairment charges.
This was driven by proactive debt management and improving economic conditions across Ireland, the bank said.
Mortgage drawdowns were 45% higher than in the first six months of 2014, it said, while lending to business customers was up 57% to £800m (€1.02 billion).
Meanwhile, Ulster Bank's parent company Royal Bank of Scotland dropped back into the red during the first half of its year after taking another £1.3 billion hit for banking scandal fines and warned of more charges to come.
The group posted half-year bottom line losses of £153m following £1.3 billion in charges after paying more than £400m to US authorities for its role in the foreign exchange rigging scandal and including compensation for payment protection insurance.
RBS also took another £1.5 billion in restructuring charges amid an ongoing overhaul at the lender and chief executive Ross McEwan cautioned of more pain to come as the bank faces further fines for "conduct issues of the past".
He said: "I don't like seeing losses and I'll not rest until these charges are behind us."