German Chancellor Angela Merkel says Greece must stick to the terms of a bailout agreement that requires Athens to sharply curtail government spending in return for further financial aid.

Tensions over Greece's massive financial bailout are set to overshadow a European Union summit Thursday amid fears that the country could accidently drop out of the euro.

Merkel says she will meet with select leaders on the sidelines of the summit, expected to include Greek Prime Minister Alexis Tsipras, French President Francois Hollande, European Central Bank President Mario Draghi and EU Commission President Jean-Claude Juncker.

Merkel told the German Parliament that "it's absolutely clear that nobody can expect a solution for Greece's problems tonight in Brussels" or on Monday, when Tsipras makes his first visit to Berlin.