Power to impose extended sentence

(1) Where an offender is convicted of an offence punishable with imprisonment for a term of one year or more (whether or not he was sentenced to such imprisonment), on two or more occasions, then, if the court is satisfied, by reason of his previous conduct and of the likelihood of his committing further offences, that it is expedient to protect the public from him for a substantial period, the court may impose an extended term of imprisonment under this section. (2) The extended term of imprisonment which may be imposed under this section for any offence may exceed the maximum term authorized for the offence apart from this section if the maximum so authorised is less than ten years, but shall not exceed ten years if the maximum so authorised is less than ten years or exceed five years if the maximum so authorised is less than five years. (3) Where an extended term of imprisonment is imposed on an offender under this section, the court shall issue a certificate stating that the term was so imposed.