Brussels  - European Union regulators Monday set a November 27 deadline for their approval of the planned takeover by Canadian auto parts group Magna International of General Motors' troubled European concern, Opel.

The date was included in the European Commission's latest list of planned mergers notifications.

However, the highly controversial deal has been thrown into uncertainty after GM recently said it was putting the deal on hold until next month, amid speculation that it may seek to retain control of its European offshoot.

The Detroit-based auto giant announced plans more than a month ago to hive off a 55-per-cent stake to a consortium led by Magna and which included the Russian bank Sberbank.

But GM's top negotiator on Opel, John Smith, wrote in a blog Friday that the US carmaker will now consider changes to the Magna deal at a meeting set for November 3.

Reacting to the news, Jonathan Todd, the spokesman for Brussels' top competition official, Neelie Kroes, said the commission expected to be informed by the German authorities about any decision taken at the November 3 meeting.

Todd also said regulators had taken note of the fact that the German authorities had clarified that any state aid would be "available irrespective of the investor or the investment plan."

The commission had earlier expressed reservations over reports that the promise of German state aid to Opel was conditional on Magna's bid being successful.

Other member states with Opel factories facing the risk of closure or downsizing had also warned Germany not to make the 4.5 billion euros (6.8 billion dollars) in state guarantees to Opel conditional on the company preserving jobs in Germany.

About half of Opel's 50,000-strong workforce is in Germany.(dpa)