* Alternatives to Libor to be found for some contracts
* Regulation could extend to other benchmarks
* Wheatley says BBA's future role an "open question"
* Rival centres expected to create own "Libor" rates
By Huw Jones
LONDON, Aug 10 (Reuters) - Libor benchmark interest rates are no longer "fit for purpose" and must be changed or replaced, Britain's regulator said on Friday as he set out proposals to restore their credibility.
The initial review by the Financial Services Authority is the first concrete step to reforming Libor after a rigging scandal that has implicated global banks and hurt the reputation of regulators on both sides of the Atlantic.
"The existing structure and governance of Libor is no longer fit for purpose and reform is needed," the FSA's managing director, Martin Wheatley, said.
"It's completely untenable that we can go forward without some level of regulatory change," Wheatley added.
The future of other benchmarks - for everything from oil and gold to stock prices - was also under scrutiny, he told a Bloomberg News event.
The London Interbank Offered Rate, known as Libor, sets prices for everything from credit card payments to complex derivatives, but its credibility has been damaged since it emerged that it had been manipulated by the big banks that set it.
Wheatley's review was ordered after British bank Barclays was fined more than $450 million for rigging Libor. Lenders such as Royal Bank of Scotland also face fines.
In his proposals, Wheatley makes clear alternative benchmarks to Libor should be used in some cases while the calculation of the rates themselves needs to be done differently to make it harder to fiddle.
"The short and medium term focus has to fix Libor and then there is a broader question about whether there are better rates going forward," Wheatley said.
"Ultimately it's a market solution as to what is used. Our responsibility is to make sure that widely used benchmarks have integrity."
Benchmarks would be based less on judgment and more on actual trades, he suggests. Banks could also be obliged to contribute to setting Libor to widen participation.
Until now, membership of the Libor rate setting panel has been the preserve of a small group of banks, which volunteer daily estimates for the rates at which they would borrow different currencies for different periods.
It was impossible to replace Libor straight away because so many contracts were linked to it and it might not be possible to replace completely because alternatives are not perfect, Wheatley told Reuters on Thursday.
Basing benchmarks on actual trades would raise the problem of what to do when there were no trades for a specific rate, but Wheatley suggested that could be addressed through "interpolation" from more frequently traded rates.
The industry will have until Sept. 7 to respond to Wheatley's review with final recommendations to be made by the end of next month. Some of those are expected to be enshrined in a new law next year, with changes to bank practices introduced earlier.
Wheatley expects London to continue with "something called Libor" -- probably based on a narrower range of currencies and periods -- while other financial centres set up their own versions with the market deciding which ones to use.
Bank of England Governor Mervyn King told fellow central bankers in July that radical reforms of the Libor system were needed and called a meeting in September to discuss it.
The tougher regulation for benchmark interest rates could be extended to stock market indices and benchmarks for commodity prices such as oil and gold, Wheatley said. Although stock indices are based on trades, the others are often set by panels and less transparent.
There was no timeline for any reform of these other benchmarks and such changes would likely need to be agreed at the global level, he said.
Supervision of Libor could be handled by a "college of supervisors" from across the world with Britain in the chair, Wheatley said.
This may not satisfy other regulators, however.
There have been calls in the United States for a locally supervised alternative to Libor. The European Union has floated the idea of the European Central Bank regulating Euribor, the euro-denominated rate.
Thomson Reuters, parent company of Reuters, calculates and distributes Libor rates on behalf of the British Bankers' Association.
Wheatley cast doubt on the banking body's future oversight role in Libor setting.
"It still remains an open question as to whether, from an industry perspective, it's still the best body to continue with that function," he said.
The BBA said on Friday the "absolute priority" was to provide a reliable benchmark which has the confidence of all.