4.—(1) Section 153 (liability for oil pollution in case of tankers) is amended as follows.
(2) For “owner” and “owners” (in each place), there is substituted respectively “registered owner” and “registered owners”.
(3) In subsection (2), the words after paragraph (b) are omitted.
(4) After subsection (2), there is inserted—
“(2A) In this Chapter, such a threat is referred to as a relevant threat of contamination falling within subsection (2) of this section.”.
(5) Subsections (7) and (8) are omitted.