FRANKFURT, Jan 19 (Reuters) - European Central Bank President Mario Draghi said on Thursday that actions the bank has taken in December have succeeded in improving the economic climate, but he pledged to do more if the improvement proved transitory.

He also said economic growth in the euro zone would be held back by the lack of structural reforms by member states and that such moves should be stepped up.

“A very substantial degree of (monetary policy) accommodation is needed,” he told a news conference after the ECB had left interest rates and asset purchases unchanged.

“If the outlook becomes less favourable ... we stand ready to increase our asset-purchase programme in terms of size or duration,” he said.

Euro zone price growth edged above 1 percent for the first time in three years last month, although this was largely due to a stabilisation in oil prices.

With inflation in Germany hitting 1.7 percent in December, ECB critics in the country have been calling for an early end to the central bank’s money-printing programme.

The ECB is blamed by sections of the German public opinion for eating into savings and bankrolling indebted governments in southern Europe through its policy of low interest rates and aggressive bond purchases. (Reporting By Francesco Canepa Editing by Jeremy Gaunt)