A splinter group is a group of people who break away from a larger group and form a separate organization, usually because they no longeragree with the views of the larger group.
splinter group in British English
noun
a number of members of an organization, political party, etc, who split from the main body and form an independent association, usually as the result of dissension
Examples of 'splinter group' in a sentence
splinter group
Security forces blame recent attacks on small splinter groups.
The Sun (2008)
He had been sitting on the EU fence for so long it almost seemed that he would form a splinter group.