European Union countries should set aside their "narrow self-interest" and rediscover a "spirit of solidarity," founding members of the bloc Germany, France, Italy, Belgium, Netherlands and Luxembourg said Tuesday.
The EU is facing multiple crises, as it struggles to prevent Britain's exit, revive its stagnant economy and maintain its borderless Schengen area amid an influx of migrants and terrorism threats.
"Europe is successful when we overcome narrow self-interest in the spirit of solidarity," a joint statement said after foreign ministers of the six countries met in Rome. "We have to be ready to strive for European solutions," it added.
Amid lack of progress on a migrant quota system for EU member states agreed last year, the ministers stated: "The priority is to fully implement our common decisions with efficiency and humanity."
Italian Foreign Minister Paolo Gentiloni, who promoted the meeting, warned that "a collection of doubts and crises risk calling into question the entire European project" and said that tackling migration issues was an immediate challenge.
Ahead of the talks, German Foreign Minister Frank-Walter Steinmeier told Italian daily Corriere della Sera that questioning basic EU principles was "playing with fire," but denied that the bloc's future was in jeopardy.
"I have no doubt that the European Union will continue to exist," the minister said.
However, there is EU disaffection among younger generations and whether that problem will be solved "will depend a lot on how we will overcome the refugee crisis," said Steinmeier, whose country took in 1.1 million migrants last year.
Steinmeier also said Britain should not leave the bloc.
"Without the United Kingdom we would lose a strong player and I cannot imagine it. The EU would be poorer, weaker and less open to the world. That is why we are working on a compromise, which at the same time should not call into question European treaties," he said.
The six founding members meeting is a format proposed by Italy and includes the country currently holding the EU's rotating presidency - the Netherlands - but leaves out sizeable member states like Britain, Spain and Poland.
Italian Prime Minister Matteo Renzi recently complained about France and Germany - the EU's biggest members - dominating decision making in the bloc. Gentiloni said there were no plans to create a larger six-member directorate.
He said Tuesday's talks offered a chance to brainstorm. "The table was very small, in today's EU we are used to very large tables, and a table for six is quite a sight," Gentiloni told reporters.