NICOSIA (Reuters) - Greece's official lenders are likely to offer it short-term debt relief by the end of this year, the head of the euro zone's bailout fund said on Tuesday.

Klaus Regling, head of the European Stability Mechanism, told reporters that there was progress in talks. "The ESM has a mandate to look at short-term measures, which we do, and we will make proposals before the end of the year," he said.

Athens has been pushing its official creditors to specify ways to ease its debt load, the highest in the euro zone as a percentage of economic output. Its leftist-led government argues that delays would keep badly-needed investment at bay, harming prospects of economic recovery. The country's third international bailout ends in 2018.

Regling said short-term relief measures would mainly aim to reduce the interest vulnerability of Greece's economy.

"There is quite a lot of agreement. We will not have a precise agreement on what to do in mid-2018 but on the short- term measures we will probably have decisions this year," he said.

The ESM chief said medium-term steps on debt would be taken when the current bailout program ends and could be followed by longer-term relief if Athens adheres to reforms.

(Reporting by Michele Kambas; Editing by Mark Trevelyan)