Updated

Germany's foreign minister says a "United States of Europe" proposed by his party's leader wouldn't spell the end of nation-states on the continent.

Martin Schulz, who heads the center-left Social Democrats, told a party meeting last week that countries refusing to sign a treaty establishing a federal "United States of Europe" by 2025 should leave the European Union.

Foreign Minister Sigmar Gabriel told German public broadcaster ARD on Sunday that the idea was "no contradiction to the Europe of fatherlands or motherlands."

Gabriel says European nations can't defend their interests alone on the global stage and "unless we stand together, our children won't have a voice in the world."

Talks between the Social Democrats and Chancellor Angela Merkel's conservative Union on extending their "grand coalition" for a new government resume Monday.