Publication of Supplementary Prospectus

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION, IN WHOLE OR IN PART, IN, INTO OR FROM ANY JURISDICTION WHERE TO DO SO WOULD CONSTITUTE A VIOLATION OF THE RELEVANT LAWS OF THAT JURISDICTION. THIS ANNOUNCEMENT IS FOR INFORMATION PURPOSES ONLY AND IS NOT AN OFFER OF SECURITIES IN ANY JURISDICTION.

THIS IS AN ANNOUNCEMENT AND NOT A PROSPECTUS OR EQUIVALENT DOCUMENT AND INVESTORS AND PROSPECTIVE INVESTORS SHOULD NOT MAKE ANY INVESTMENT DECISION ON THE BASIS OF ITS CONTENTS. THIS ANNOUNCEMENT DOES NOT CONSTITUTE OR FORM PART OF, AND SHOULD NOT BE CONSTRUED AS, ANY OFFER, INVITATION OR RECOMMENDATION TO PURCHASE, SELL OR SUBSCRIBE FOR ANY SECURITIES IN ANY JURISDICTION AND NEITHER THE ISSUE OF THE INFORMATION NOR ANYTHING CONTAINED HEREIN SHALL FORM THE BASIS OF OR BE RELIED UPON IN CONNECTION WITH, OR ACT AS AN INDUCEMENT TO ENTER INTO, ANY INVESTMENT ACTIVITY.

Premier Oil plc"Premier"Publication of Supplementary Prospectus26 March 2021

Premier is pleased to confirm that the Financial Conduct Authority (the "FCA") has today approved Premier's supplementary prospectus (the "Supplementary Prospectus") in relation to the proposed all share merger between Premier and Chrysaor Holdings Limited ("Chrysaor") and the reorganisation of Premier's existing debt and cross-currency swaps. The Supplementary Prospectus supplements the prospectus published by Premier on 16 December 2021.

The Supplementary Prospectus was required in connection with the occurrence of the following events: (i) the announcement by Premier of its full year results for the year ended 31 December 2020 on 18 March 2021 and publication of its report and accounts for the year ended 31 December 2020 on 25 March 2021; (ii) the publication by Chrysaor of its full year results for the year ended 31 December 2020 on 18 March 2021; and (iii) the announcement of additional proposed directors of Premier.

The Supplementary Prospectus has been submitted to the FCA's National Storage Mechanism (the "NSM") and will be available for inspection on the NSM's website at https://data.fca.org.uk/#/nsm/nationalstoragemechanism. The Supplementary Prospectus will also be available on Premier's website at www.premier-oil.com.