BERLIN (Reuters) - Greece can stay afloat if it receives its next tranche of aid later than October but will be broke if the money does not arrive, Prime Minister Antonis Samaras said, as he launches a charm offensive seeking additional time for Athens to meet its bailout commitments.

"Theoretically, we could bridge the time. But if we don't get the tranche at all, Greece is broke," Samaras told the Thursday edition of the Sueddeutsche Zeitung newspaper.

He also said he personally guaranteed that Germany and other creditor countries, which are increasingly tiring of bailing out Greece, would get their money back.

"The Germans will get their money back. I am guaranteeing that personally. And all the others will also get their money back. We will fulfill our obligations fully."

Appointed in June after two tumultuous parliamentary elections, Samaras hopes to persuade Eurogroup chief Jean-Claude Juncker on Wednesday that the debt-laden Greek nation has the will to ram through unpopular reforms and deserves more time to do it, without being cut off from European rescue loans.

He also meets German Chancellor Angela Merkel on Friday and French President Francois Hollande a day later.

(Reporting by Annika Breidthardt)