The heads of the German and French central banks warned in a joint article on Monday that the influx of refugees to Germany wouldn’t solve that country’s labor shortage problems, but would put a damper on economic growth in the longer term.

Jens Weidmann and François Villeroy de Galhau, president of the Bundesbank and the Banque de France, respectively, wrote in the German newspaper Süddeutsche Zeitung that the new challenges facing Europe, ranging from the hangover from the global financial crisis to high unemployment, terrorism and the refugee crisis, required fresh responses.

“As convinced Europeans, we both believe the future of Europe lies not in renationalization but in shoring up its foundations,” they said.

Germany needs to deal with its dwindling workforce, which would not necessarily be solved by the current influx of refugees, they said, adding: “This will slow down economic growth in the longer term.”

“More decisive political measures are needed to equip refugees who have the right to stay with the relevant language and vocational skills to participate successfully in the job market,” they wrote.

They urged France to introduce reforms to the job market and the service sector, and to get its public debt down to a “more sustainable level” via tighter spending policies.

As for the eurozone overall, the central bank chiefs said monetary policy had done a lot to help the economic situation, “but will not be enough to create sustainable growth.”

They called for deeper integration of the eurozone via a “financing and investing union,” whose goal would be to encourage Europeans to invest savings in the real economy. This would spread the risk more broadly, contributing to stability.

The European Commission has already launched several initiatives to boost investments in the eurozone, such as the Capital Markets Union, the Juncker Investment Plan and the banking union, which has already put the largest banks in the eurozone under European Central Bank supervision and introduced a common mechanism for winding down failed banks.

The German and French central bankers said these projects would require more sharing of sovereignty by EU countries, a more unified European administration and the creation of a finance ministry for the eurozone. Both central bankers also call for a “stronger political structure…under the control of the European Parliament.”

However, Weidmann toned down his comments about a eurozone finance minister, telling the Frankfurter Allgemeine Zeitung that the idea was unenforceable.