BEIRUT - Lebanon's central bank said on Wednesday it would sell U.S. dollars in cash at a rate of 70,000 pounds per dollar on its Sayrafa platform starting on March 2 and until further notice.

The surprise announcement came as the parallel market exchange rate for the Lebanese pound hit an all-time low of 90,000 per U.S. dollar on Wednesday.

The statement, signed by embattled central bank governor Riad Salameh, said the body was "intervening" by revaluing the rate on its Sayrafa platform for both individuals and companies.

The Sayrafa rate on Tuesday was 45,400 per U.S. dollar. Wednesday's change means the Sayrafa platform was now valuing dollars at more than four times the official government exchange rate.

The central bank had re-valued the official rate to 15,000 pounds per U.S. dollar on Feb. 1 - already a 90% devaluation from the longtime peg of 1,507.5.

The finance ministry on Tuesday received a green light to triple the rate at which customs tariffs would be paid in local currency from 15,000 Lebanese pounds to 45,000 per U.S. dollar.

Unifying multiple exchange rates is one of several steps sought by the International Monetary Fund for Lebanon to clinch a $3 billion aid package that would help it to emerge from the meltdown.

But the IMF said last year progress in implementing reforms remained "very slow", with the bulk yet to be carried out despite the gravity of a crisis marking Lebanon's most destabilising phase since the 1975-90 civil war.

(Reporting by Maya Gebeily Editing by Chris Reese and Alistair Bell)