(CNN) -- Zimbabwe's President Robert Mugabe has signed a new law that hands over majority ownership of all businesses to "indigenous" Zimbabweans.
President Robert Mugabe attends a rally earlier this month ahead of elections set for March 29.
The new law means that foreign- and white-owned companies operating in the country will have to surrender at least 51 percent control of their operations to blacks.
Lawmakers passed the legislation last September. But the presidential "assent" was announced Sunday in the government-controlled newspaper, The Sunday Mail.
It comes just days before Mugabe could face the most serious challenges to his decades-long rule in the March 29 presidential and parliamentary elections.
Under his rule, once-prosperous Zimbabwe has suffered an economic crisis with routine shortages of food, electricity and foreign currency.
Unless the Minister of State for Indigenisation and Empowerment alters the share allotment, the law would mean that several banks, mining companies and phone companies -- among other foreign businesses -- will have to relinquish control.
The bill, when it was put forward last year, described "indigenous Zimbabwean" as "any person who, before the 18th April, 1980, was disadvantaged by unfair discrimination on the grounds of his or her race, and any descendant of such person."
Zimbabwe won independence from white rule on that date.
For the next 28 years, Mugabe, 84, has been the country's only ruler. In the upcoming elections, he faces two formidable opponents: a heavyweight within his own party and a leading opposition figure.
Movement for Democratic Change leader Morgan Tsvangirai this month said that he and his party will participate in the elections.
Mugabe survived a hotly contested presidential challenge from Tsvangirai in 2002, amid widespread accusations of vote-rigging.
The president's other challenger is former Finance Minister Simba Makoni, who recently announced his bid to unseat Mugabe and was promptly booted out of the ruling ZANU-PF party.
The country of 12.5 million is in dire financial straits. The most recent estimate of the nation's inflation rate said it exceeded 24,000 percent, but economists say it is much higher.
While there is no official figure, unemployment among Zimbabweans is estimated at 80 percent. E-mail to a friend
CNN's Kim Norgaard in Johannesburg, South Africa, contributed to this report.
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