(1) The Secretary of State may issue a certificate under this section in respect of a person if the Secretary of State reasonably-
(a) believes that the person's presence in the United Kingdom is a risk to national security, and
(b) suspects that the person is a terrorist.
(2) In subsection (1)(b) "terrorist" means a person who-
(a) is or has been concerned in the commission, preparation or instigation of acts of international terrorism,
(b) is a member of or belongs to an international terrorist group, or
(c) has links with an international terrorist group.
(3) A group is an international terrorist group for the purposes of subsection (2)(b) and (c) if-
(a) it is subject to the control or influence of persons outside the United Kingdom, and
(b) the Secretary of State suspects that it is concerned in the commission, preparation or instigation of acts of international terrorism.
(4) For the purposes of subsection (2)(c) a person has links with an international terrorist group only