BERLIN (Reuters) - A letter from Greece to euro zone ministers outlining reforms intended to unblock loans is not in itself enough to sway them as implementation will be key, European Commission Vice President Valdis Dombrovskis was quoted on Sunday as saying.

In the letter to the Eurogroup, Greece's Finance Minister Yanis Varoufakis said Athens aimed to save 200 million euros by slashing public sector spending, offsetting an estimated 200 million euro cost to tackle what the new left-wing government calls the country's "humanitarian crisis".

"A letter here or there isn't going to change much," Dombrovskis told the Frankfurter Allgemeine Zeitung newspaper.

Dombrovskis, who oversees the euro in the Commission, said individual reforms first had to be agreed in Greece, passed by parliament and then implemented.

He also said he did not expect the Eurogroup to make any decisions on Greece on Monday at their meeting in Brussels.

Dombrovskis told the newspaper that loans to Greece can only be paid out if the government fulfils the conditions.

"The government in Athens apparently has a different understanding of the problem than we do," he added. "We have to keep repeating a point: if the program is to be successfully completed, the government has to fulfil the conditions."

Jeroen Dijsselbloem, the head of the Eurogroup, said the letter he received from Athens on Friday asking for an immediate resumption of talks with creditors was "helpful", but needed to be scrutinized by representatives of Greece's creditors.

Once steps to reach these goals are taken, Greece would become eligible for more credit from the euro zone and the International Monetary Fund, and its banks could again finance themselves at European Central Bank open market operations. But time is pressing as Greece will run out of cash later this month.

(Reporting by Erik Kirschbaum; Editing by Gareth Jones)