BERLIN (Reuters) - Greece's third bailout program could fall apart as the International Monetary Fund has not yet made up its mind whether to take part in providing more aid, European Commission President Jean-Claude Juncker said.

"Yes, it is on a shaky ground in the sense that we don't see how the International Monetary Fund could manage this problem," Juncker told German radio Deutschlandfunk in an interview to be aired on Sunday.

"No country has managed bigger steps to improve competitiveness than Greece."

(Reporting by Joseph Nasr Editing by Jeremy Gaunt)