Zimbabwe's central bank says banknotes from its old currency, which collapsed and was discarded years ago because of runaway inflation, can be exchanged for American dollars. But 100 trillion Zimbabwean dollars will fetch only 40 U.S. cents.

That's a fraction of what collectors have been paying for the notes with numerous zeroes for years.

Zimbabwe in 2009 abandoned its currency for a system dominated by the U.S dollar and the South African rand after inflation hit 230 million percent. Back then, even street hawkers refused to accept a $100 trillion dollar note that was issued.

Starting Monday, stacks of Zimbabwean bills that might still be kept by Zimbabweans can be exchanged for U.S dollars. The offer is part of what the central bank says is an overdue plan to phase out the currency entirely.

Worth far more on black market

Some people in Harare, Zimbabwe's capital, said they disposed of their Zimbabwean dollars long ago.

"I used it as garden manure," said Isaac Mutezowepasi, a street vendor. "Why would I have kept that dirt?"

Others said they still have heaps of old dollar notes at home, but won't respond to the government offer.

"I am keeping them for my grandchildren to see. Plus I know I will get more for them in future because these Zimdollars are going to be in demand," said Tendai Nyaundi, a graphic designer.

On e-Bay on Friday, five banknotes of 100 trillion Zimbabwean dollars were being sold for $159. Another e-Bay post put five banknotes of $100 trillion at $173.99.

There have been calls to re-introduce the Zimbabwean dollar by some members of President Robert Mugabe's ruling ZANU-PF party. They argued that the use of foreign currencies is responsible for the country's current liquidity problems.

Finance Minister Patrick Chinamasa has repeatedly said the U.S dollar "is here to stay."