Foreign participation in maritime auxiliary services is limited to 51% as per indication in Brunei Darussalam's CPTPP list of on Non-Conforming Measures (Annex 1) including restrictions that are supposedly reflective of underlying regulations.
"ANNEX I - SCHEDULE OF BRUNEI DARUSSALAM
Sector: Transport Services
Sub-sector: Maritime passenger transport services, Maritime freight transport services, Services auxiliary to maritime transport
Obligations Concerned: National Treatment (Article 9.4), Performance Requirements (Article 9.10), Senior Management and Boards of Directors (Article 9.11), 
Market Access (Article 10.5), Local Presence (Article 10.6)
Measures: Administrative Measures and Guidelines
Description: Investment
1. Foreign nationals and enterprises may not provide maritime passenger and freight transport services as Brunei Darussalam-flagged vessels in Brunei Darussalam, unless:
(a) they register such vessels under the Brunei Darussalam flag through an enterprise established in Brunei Darussalam that is a joint venture, where the foreign national or enterprise does not own more than 40 per cent equity shareholding in the joint venture; (b) they comply with any performance requirements imposed, including a requirement to transfer a particular technology or other proprietary knowledge as long as such requirement to transfer technology or other proprietary knowledge does not unreasonably prejudice the legitimate interests of the owner of technology or proprietary knowledge and is not for the purposes of commercial exploitation by Brunei Darussalam; and (c) a majority of the senior managers in the joint venture are Brunei nationals.
2. Foreign nationals and enterprises may not provide services auxiliary to maritime transport services at Muara Port, unless:
(a) through an enterprise established in Brunei Darussalam that is a joint venture, where the foreign national or enterprise does not own more than 51 per cent equity shareholding in any such enterprise providing services auxiliary to maritime transport services; and (b) a majority of the senior managers in any such enterprise established are Brunei nationals.
3. The number of enterprises in Brunei Darussalam providing maritime passenger and freight transport services and services auxiliary to maritime transport at Muara Port may be subject to needs-based quantitative limits." (ANNEX I - SCHEDULE OF BRUNEI DARUSSALAM, Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP)) 
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"PART 12 - LICENSING OF MARINE AND PORT SERVICES AND FACILITIES 
Public licences authorising provision of marine or port services and facilities 
81. (1) No person shall provide - (a) any marine service or facility; or (b) any port service or facility, unless he is authorised to do so by a public licence or an exemption granted by the Authority. 
(2) Every public licence granted under this section shall be in such form and for such period and may contain such conditions as the Authority may determine. 
(3) The Authority may, with the consent of, or in accordance with the terms of a general authority given by the Minister, grant a public licence either unconditionally or subject to such conditions as the Authority may impose and specify in the public licence and either irrevocably or subject to revocation as therein specified, authorising any person to provide any marine service or facility or any port service or facility. 
(4) Without prejudice to the generality of subsection [3), a public licence may be granted either to any person, class of persons or a particular person, and may include conditions requiring the public licensee - (a) to enter into agreements or arrangements with any other person, class of persons or another public licensee for - (i) the interconnection with, access to and use of any installation of the licensee (wherever situated and whether or not used for the purpose of carrying on the activities authorised by the licence) ; and (ii) such other purpose as may be specified in the licence, and on such conditions as may be agreed to by the licensee and such other persons or, in default of agreement, as may be determined by the Authority; [...]
(5) Conditions in a public licence may contain - (a) control and restriction, directly or indirectly, on the creation, holding or disposal of shares in the public licensee or its shareholders or interests in the undertaking of the public licensee or any part thereof; (b) restriction on the carrying on by the public licensee of any trade or business which is not related to the activity which the licensee is authorised by its public licence to carry on; [...]" (MARITIME AND PORT AUTHORITY OF BRUNEI DARUSSALAM ORDER, 2017)

ANNEX I - SCHEDULE OF BRUNEI DARUSSALAM, Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP)
MARITIME AND PORT AUTHORITY OF BRUNEI DARUSSALAM ORDER, 2017
[<a href="https://www.mfat.govt.nz/assets/Trade-agreements/TPP/Annexes-ENGLISH/Annex-I.-Brunei.pdf">CPTPP</a>],[<a href="https://www.agc.gov.bn/AGC%20Images/LAWS/Gazette_PDF/2017/EN/S022.pdf">Order</a>]