* FCA says new disputed listing category starts in July
* Big investors want review of category within two years
* Lawyer says wide range of firms may be interested (Adds Aramco, City of London, TheCityUK)
By Huw Jones
LONDON, June 8 (Reuters) - Britain's markets watchdog will press ahead with a new premium listing next month aimed at attracting companies like state-controlled Saudi Aramco to London, although the rules have been "refined" following investor criticism.
The Financial Conduct Authority's initial proposal last year led to suggestions the British government had influenced the watchdog to try to secure the Saudi energy company's planned initial public offering (IPO).
Saudi Arabia is expected to float up to 5 percent of Aramco in Riyadh and an international venue such as London or New York in what is expected to be the biggest ever IPO and would boost the reputation of its chosen listing venue.
Saudi Aramco had no immediate comment.
The City of London and TheCityUK which promote Britain as a business centre, welcomed the new rule as long as strong corporate governance standards are maintained.
Britain is keen to promote London's leading position as a financial centre as it leaves the European Union but some lawmakers had questioned if the original proposal for listings by sovereign-controlled firms could weaken investor protection.
The FCA said it was pressing ahead, despite criticism of its plans by major institutional investors when they were first circulated in July last year.
"The FCA thinks there is considerable benefit to investors if corporate issuers agree to meet these additional premium requirements," the watchdog said in a statement accompanying an 83-page document outlining the new rules on Friday.
The FCA said it had made some changes following feedback, including the requirement that the election of independent directors be subject to approval from independent shareholders.
There would also be a requirement for "timely disclosures" on transactions between the sovereign and the issuer.
But there will not be a requirement for a controlling shareholder agreement, and no need for an advance sponsor opinion or advance approval by independent shareholders of certain transactions with the sovereign or its associates.
"These rules mean when a sovereign controlled company lists here, investors can benefit from the protections offered by a premium listing," FCA Chief Executive Andrew Bailey said.
The watchdog said responses to its consultation were "polarised", with big investors mostly against, and all others generally supportive.
The Investment Association, which represents big shareholders, said it was disappointed by the lack of a requirement for independent votes on the changes made. It also wants a review of the new listing category after two years to check for any unintended consequences.
"We continue to oppose the inclusion of companies in this new segment in all major equity indices as this would force UK savers to invest in these companies despite the loss of valuable and hard won investor protections," the IA's chief executive Chris Cummings said in a statement.
Nick O'Donnell, a partner at law firm Baker McKenzie, said that overall the FCA had stuck to its guns while central planks of corporate governance standards, such as being part of a FTSE index not being automatic, remain intact.
"Although the proposal has often been linked with the possible Saudi Aramco IPO, the reality is this is much wider than that. There are a lot of other companies that have been looking at this segment," O'Donnell said.
A premium listing in London would typically require a float of at least 25 percent of a company's shares, but the new category could allow a smaller float, the FCA said.
"Some very large companies can make a credible case for a liquid market at a free float of less than 25 percent," it said.
Additional reporting by Rania El Gamal in Riyadh, Editing by Ben Martin and Alexander Smith