Zimbabwe's main opposition party says it will begin its "final push" against President Robert Mugabe next week.
Tsvangirai warns his supporters to be ready for trouble
A spokesman for the Movement for Democratic Change told BBC News Online that the party was calling for prayer meetings culminating in marches to start on 2 June.
Paul Themba Nyathi said the protests would not stop until "Mr Mugabe gives a clear signal that he will leave office".
The MDC accuses Mr Mugabe of rigging elections last year and using state security agents to persecute his opponents.
We must be prepared to make a mark to ensure that we will never again be oppressed
Morgan Tsvangirai, MDC leader
This is the first time the MDC has given the date for its long-announced "mass action".
The MDC leadership has been criticised by some of its activists for not doing more to make life difficult for the government.
The latest sign of the economy meltdown is a shortage of bank notes.
There were long queues outside banks on Saturday morning ahead of Monday's public holiday despite limits on cash withdrawals.
There have been shortages of basic commodities such as bread, sugar and petrol for several months.
The latest statistics show annual inflation is running at 269%.
Some eight million people require food aid, according to aid agencies.
The opposition blame the shortages on economic mismanagement, while Mr Mugabe says they are a result of a western plot to bring him down.
As the pressure on Mr Mugabe's government has increased, so-called "war veterans" loyal to his Zanu-PF party have threatened to use force to prevent any opposition protests.
Zimbabweans are getting used to queues
"Using our military experience, we will mobilise," warned Patrick Nyaruwata, chairman of the Zimbabwe National Liberation War Veterans' Association.
"We will co-ordinate with state security agents to fight."
But MDC leader Morgan Tsvangirai told thousands of supporters that he was not afraid.
"We must be prepared to be arrested, we must be prepared to make a mark to ensure that we will never again be oppressed," he said.
"Prepare for a final push, with democracy marches in every city, and from every workplace," he told a Harare rally on Sunday.
The main trade union umbrella organisation has urged workers to stock up on the staple food, maize-meal, and cash ahead of the mass protests.
Meanwhile, South Africa has rejected a request to curb media criticism of Mr Mugabe, reports the French news agency, AFP.
Zimbabwe Information Minister Jonathan Moyo asked the South African Government to stop the "demonisation" of Mr Mugabe in South African media.
"South Africa has laws that govern the freedom of the press and we have no intention of interfering with that," President Thabo Mbeki's spokesman Bheki Khumalo told AFP.