Cypriot media had cited sources saying there was no question of revoking citizenship.

The department said it was making changes to strengthen the process around revoking citizenship in such cases.

The test of proof for revoking citizenship was much higher than that for determining someone's refugee status.

Johnson said his agency was reviewing the cases and revoking citizenship for cases in which it was wrongly granted.

UK Prime Minister David Cameron has spoken of tough measures, including imprisonment, seizing the passports of jihadis and possibly revoking citizenship.

President-elect Donald Trump has suggested there should be punishments for people who burn the US flag, such as a year in prison or revoking citizenship.