However, the effects have been more moderate than elsewhere in the eurozone and the long-term impact is difficult to gauge, though retail banks have already been negatively affected.

Bond purchases and other non-standard measures that the ECB has resorted to reduce the yield on government bonds, which has reduced borrowing costs and brought down interest rates on corporate and household loans, the Slovenian central bank estimates.

The measures also had a positive impact on exporters as the weak euro made Slovenian exports to non-euro countries more competitive. Preliminary data also show the expansionary fiscal policy boosting household spending.

But the central bank warns that it is still too early to make a comprehensive estimate of the effects, as such measures usually trickle down into the economy with a delay.

The stated goal of the ECB measures has been to prop up the economy and raise inflation, but the flip side is that banks have been squeezed by narrow margins.

France Arhar, the former central bank governor who now heads the Bank Association, told the STA that the ECB policy is a risk for banks in that interest revenue, a key source of income, is declining.

With banks making money on the difference between rates on loans and rates on deposits, the logical step would be to start lowering the rates on deposits - but these are already at or near zero.

Arhar says it is unlikely commercial banks would start charging for deposits, but the other solution, higher account fees, are equally infeasible.

"The price would have to rise drastically, but it is not realistic to expect banks charging 15 euros [per month] in account management fees," he said.

Unicredit banka Slovenije, the Slovenian subsidiary of the namesake Italian banking group, said ECB measures suggest interest on deposits as well as loans will continue to drop.

"The ECB measures do not have an impact on the pricing of other banking services such as packages," the bank said.

NLB, the market leader, noted that commercial banks do not expect particular benefits given the excess liquidity. "We are still preparing our strategy for the balancing of the negative effects on interest revenue."

According to Matej Šimic, an analyst at asset management firm Alta, low interest rates should theoretically buoy borrowing and household spending, but this is yet to happen. Indeed, it is questionable whether the ECB measures will achieve their aim.

"In normal circumstances banks would offset low interest margins with crediting growth, but now they have to rely on other sources to improve profitability."

Instead, banks have been propping up their revenue with higher fees. "Even if these price hikes amounted to only a few cents, this still represents an increase of several percent compared to previous years," he said.

They have been more aggressively pushing additional services such as insurance and mutual funds.

This will have to be coupled with cost optimisation. "IT and statistical data processing offer banks the opportunity to reduce costs and improve utilisation of sales channels," he said.