Ministers and officials are "considering the implications" of a report commissioned by the Prime Minister into the Muslim Brotherhood, Downing Street said following reports its publication had been delayed.
The review was led by Sir John Jenkins, the UK's ambassador to Saudi Arabia, a country which has declared the Egyptian group a terrorist organisation.
But the Financial Times reported that Sir John's investigation found little evidence to support banning the group in Britain, potentially upsetting Gulf states who had pushed for tougher action.
Since the Muslim Brotherhood-backed Mohammed Morsi was ousted as president of Egypt last summer the group has been blamed for a series of violent acts, which it has denied.
A No 10 spokeswoman said: "The PM asked the Government's officials to look into this, to get a better handle of what the Muslim Brotherhood stands for, how they intend to achieve their aims and what that means for us here in Britain."
The main findings were completed by the end of July, the spokeswoman said, adding that the report would be completed "in due course".
"Work is now ongoing across government to consider the implications of the findings."
She added: "The Muslim Brotherhood is not proscribed. There is a clear process for doing that, which is the established process under the Home Secretary with the criteria set out in the Terrorism Act 2000.
"We have said that we will make the findings public in due course."