BRUSSELS — Leaders of France and Germany said Sunday they made progress in settling their differences over a strategy to solve Europe’s debt crisis, but the “mind-boggling technical complexity” of the task meant they needed a few more days to finalize plans.

Negotiations are continuing between Paris and Berlin, the two heavyweights of the European Union, over how best to increase the power of the EU’s $600 billion bailout fund and to reduce Greece’s staggering debt. Many analysts have warned that the debt crisis is fast approaching a make-or-break point.

A comprehensive solution had been expected to come out of Sunday’s gathering of the leaders of all 27 EU nations in the Belgian capital. But French President Nicolas Sarkozy and German Chancellor Angela Merkel said they would present their plan at a follow-up summit Wednesday.

“Things are forging ahead. We have yet to reach a final conclusion,” Sarkozy said.