European Central Bank President Mario Draghi has said he is confident that the referendum on new EU budgetary rules will be passed in Ireland.

Mario Draghi was speaking to reporters after the bank's regular meeting in Frankfurt, at which it held its main interest rate steady at 1%.

Mr Draghi was asked about a restructuring of the promissory notes being used to finance the former Anglo Irish Bank.

He said the issue was "under study" but was not discussed at today's meeting.

The ECB chief said he was confident on the referendum vote because Ireland had made the most progress of all the eurozone countries which had been bailed out.

But he said he was aware that there were "fragilities that need to be taken care of".

Meanwhile, the ECB has lowered its forecast for euro zone economic growth this year.

Mr Draghi told reporters the bank's experts had lowered forecasts for euro zone growth this year to a range of between -0.5% and 0.3%. The forecast for 2013 was also lowered to between zero and 2.2%. The downgrade was blamed on the effects of the euro zone debt crisis and higher energy prices.

Mr Draghi said, however, that there were signs of a stabilisation in the euro zone economy, and a gradual recovery was expected this year. But he said the euro zone debt crisis would continue to dampen growth momentum.

He also said inflation would stay above its 2% target this year, due to higher energy prices and increases in indirect taxes such as VAT in euro zone countries. The bank's inflation forecast for this year has been raised to 2.4%.

Mr Draghi said the impact of ECB special measures, including its two massive injections of cheap money to banks, had been positive, with a "significant improvement" in the financial environment.

The ECB cut rates twice late last year to a record low of 1%. Today's decision to hold the main refinancing rate at that level was in line with expectations.

The latest Reuters poll of 74 economists suggests the ECB will hold rates at 1% until well into 2013. Mr Draghi told reporters the bank's governing council did not discuss any interest rate changes at today's meeting.

The euro zone economy has stabilised over recent months, in part thanks to the ECB's back-to-back rate cuts in November and December and the twin funding operations, which brought calm to euro zone debt markets.