BERLIN (REUTERS) - The euro zone needs a joint budget to increase investment and Germany should be prepared to do more in Europe, possibly by increasing its financial contribution to the bloc, SPD leader Martin Schulz said in a strategy paper presented on Sunday (July 16).

"Germany is a great country. But Germany can do more," Schulz, whose SPD is the junior party in Germany's coalition government, said in the introduction of his 10-point-plan for a modern Germany and a better Europe.

Schulz, a former European Parliament President, said EU countries outside the single currency bloc should not be able to veto further euro zone integration and that those ignoring solidarity on important issues must face financial sanctions.

Schulz is hoping to beat Chancellor Angela Merkel in a Sept 24 election but the SPD has lost momentum in the polls after gaining at first following his nomination in January.