The southern African country has a multiple exchange rate system where the Zimbabwe dollar is officially pegged at Z$30,000 to the dollar while the national revenue authority uses a rate of Z$270,000 per dollar.

But on the black market it is trading at up to Z$40 million per dollar and analysts say it is likely to continue weakening in tandem with the economy.

"We are going to float the Zimbabwe dollar because we realise everyone is now trading on the black market so if you float it no one is going to be hurt," said Tendai Biti, the secretary general of the larger faction of the main opposition Movement for Democratic Change at the launch of his party's policy document.

The MDC has promised to turn around an economy grappling with the world's highest inflation rate at over 100,000 percent by raising production in key mining, agriculture and manufacturing sectors if elected to power in general elections on March 29.

The key contest is the presidential race which pits President Robert Mugabe against rival MDC leader Morgan Tsvangirai and former finance minister Simba Makoni who was expelled from the ruling ZANU-PF party last month.

Zimbabwe's economic crisis is also marked by rising unemployment, shortages of food, fuel and electricity. Mugabe denies mismanaging the economy which he blames on Western sanctions.