ACCRA, Aug 7 (Reuters) - Ghana's central bank has blamed foreign exchange speculators for a lack of cedi notes in the banking system and for the related lack of foreign currency.

Bank of Ghana Governor Kwabena Duffuor told the state-owned Daily Graphic in an interview on Monday that speculators had withdrawn billions of cedis in cash from the banks to buy foreign exchange. He did not say over what period.

"We're not stopping people from taking cash from the banks," Duffuor said.

"The Bank of Ghana wants to encourage the use of cheques and bank drafts for payment of large sums of money. We're bankers and we know what is good banking practice," he said.

However, analysts said that the central bank had been mopping up cedis from the banking sytem in the past week or two via money market repurchase agreements.

Money has also been flowing into Treasury bills, where the discount rate on 91-day bills stood at 41 percent at the end of July, they said.

The bank is tightening monetary policy to support the cedi as well as to choke off inflation, estimated at a year-on-year 19.8 percent in June, up from 18.7 percent in May and 13.8 percent at the end of 1999.

The cedi has lost around 45 percent of its value this year and was quoted on Monday at 6,200 per dollar.

Banks have begun rationing cedi notes and are increasingly paying a big portion of withdrawals in 500-cedi coins, to the anger of customers.

One customer complained on radio on Monday that when he had withdrawn 10 million cedis ($1,610) from his bank recently, one million had been paid in the form of 2,000 coins.

"When we go to the central bank they tell us there're no notes, only coins," an official at one of the leading banks, Standard Chartered, said.

The foreign exchange shortage is just as real, and some customers have taken to depositing large sums of cedis with foreign exchange bureaux in order to jump the queue whenever currency becomes available.

Government officials blame the fall in the cedi on low world prices for Ghana's gold and cocoa exports and high crude oil prices, compounded by speculation.