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BEIRUT, April 24 (Reuters) - The Lebanese central bank set an exchange rate of 3,625 Lebanese pounds per dollar to be applied by money transfer companies on Friday, a central bank source said, 58% weaker than the official peg as the country grapples with a major financial crisis.

The Lebanese pound has slumped on a parallel market since October when the country's long-brewing economic troubles came to a head, prompting the financial and banking crisis.

"Prices may change every day and will be set the day before," the central bank source said, adding that the rate was based on the price dollars were fetching at foreign exchange offices.

"In the event that there are major fluctuations during the day, the price may be set again during the same day," the source added.

The authorities are still applying the official peg of 1,507.5 pounds per dollar for essential imports - fuel, wheat and medicine - even as the currency has slumped on the parallel market.

Officials say keeping the official rate for such goods aims to put a brake on accelerating inflation.

With dollars in short supply, Lebanon's central bank earlier this month said money transfer services operating outside commercial banks must issue cash in local currency at a "market rate".

Parliament speaker Nabih Berri urged the government on Thursday to use its legal powers to halt the "dramatic collapse" of the country's pound currency before it is "too late".

Earlier this week, the central bank said depositors with dollar accounts in Lebanon would be paid cash in local currency, also at a "market rate" within each bank's withdrawal limits.

It was not immediately clear if the rate announced on Friday would be applied by commercial banks for such withdrawals. (Writing by Tom Perry; Editing by Toby Chopra)

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