21.— (1) Where a person is convicted of an offence under F41[under section 4, 5, 12, 13B, 14 or 17A], committed after the commencement of this section, the court shall, unless it is satisfied that there are special and substantial reasons for not so doing, order the person to pay to the court a contribution towards the costs and expenses incurred by the Bureau in the performance of its functions not exceeding such amount as may, for the time being, stand prescribed.

(2) Payments under subsection (1) shall be disposed of in such manner as may be prescribed.