The new banknotes have failed to curb inflation
Zimbabwe's annual inflation rate - already the world's highest - has soared to 231,000,000%, newly released official figures for July show.
The rise - from 11,200,000% last month - was largely due to increases in the prices of bread and cereals.
A landmark power-sharing deal between President Robert Mugabe and opposition leader Morgan Tsvangirai has failed to ease the country's economic crisis.
Meanwhile, the UN says it needs $140m for food aid over the next six months.
The UN World Food Programme estimates that two million people are in need of food aid, and that the figure will rise to 5.1 million - or 45% of the population - by early 2009.
"Millions of Zimbabweans have already run out of food or are surviving on just one meal a day - and the crisis is going to get much worse in the coming months," said WFP official Mustapha Darboe.
The inflation figures are from July - before the power-sharing deal - but reports from Zimbabwe suggest that the prices of many goods has continued to shoot up, while the value of the Zimbabwe dollar is plummeting.
In September, it was agreed that Mr Mugabe - Zimbabwe's leader for the last 28 years - would remain president while Mr Tsvangirai would become prime minister.
Some outlets have been licensed to sell goods in US dollars
But more than three weeks later, the two sides have yet to reach agreement on the make-up of the new cabinet.
On Thursday, Mr Tsvangirai repeated calls by his Movement for Democratic Change (MDC) for South Africa's former President Thabo Mbeki to resume his role as mediator and help break the stalemate.
"We have declared a deadlock and therefore the process cannot move forward except in the presence of the facilitator," he said.
Negotiations are deadlocked over who will control key ministries including defence, finance, home affairs and state security.
But Mr Mugabe's Zanu-PF has rejected the MDC's call, saying no outside mediation is needed.
The president had said a government would be formed last week.
Unemployment is reported to be about 80% of the adult population.
In a bid to combat the shortages of many basic goods, the government has allowed some shops to sell in foreign currency.
Critics of Mr Mugabe say he triggered the economic crisis when he began seizing white-owned farms for land redistribution ahead of parliamentary elections in 2000.
But Mr Mugabe blames Western sanctions which target him and his chief supporters for wrecking Zimbabwe's economy.