The US authorities have asked Diageo for additional information before approving the drinks company's partnership with the Nolet family.

The Federal Trade Commission (FTC) has made a request for additional information under the US Hart-Scott-Rodino Antitrust Improvements Act (HSR) in connection with Diageo's agreement with the Nolets to form a 50/50 company for the sale and distribution of the Ketel One vodka brand.

The request, widely known as a 'second request', will extend the waiting period imposed by HSR until, at the latest, 30 days after Diageo has "substantially" complied with the second request.

The company said it would comply with the second request "as expeditiously as possible", and will "continue to cooperate fully with the FTC's review".

Diageo looked to calm concerns that there may be a stumbling block to the Ketel One deal. "This is not unusual," a spokesperson for the company said. "A 'second request' is often part of the FTC review process."

Diageo announced the formation of the joint company last month. The US$900m deal prompted confirmation from the UK-based company that it would not participate in the auction to sell off Vin & Sprit, the Swedish state-owned producer of Absolut vodka.