It was the second celebration for Schröder, who has just turned 70, and already had one party with Russian President Vladimir Putin in St Petersburg.
This time he was the guest of Rothschild banking group, where Schröder is a member of an international advisory committee.
The party at the five-star Schlosshotel Kronberg near Frankfurt am Main was abruptly stopped shortly after 7.30pm when staff received a phone call saying something awful was going to happen.
Bild newspaper reported the guests were being served their aperitifs and the starters were being prepared when everyone had to leave.
Police used sniffer dogs to search the building but found nothing and Schröder's party, which had been moved to a nearby hotel, was allowed to return.
Bild reported guests included Russia’s ambassador to Germany Vladimir Grinin, Deutsche Bank’s co-CEO Jürgen Fitschen, RWE head Peter Terium and Hartmut Mehdorn – the chief executive of Berlin Brandenburg Airport.
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