Farm invasions began more than 18 months ago
The move means that farmers who have been issued with acquisition orders by the government will have to stop farming immediately and remain confined to their houses, which they will have to vacate after three months.
Previously, land-acquisition orders had to pass through the courts first, now the courts will examine cases retrospectively which correspondents say could take months.
Zimbabwe's white farmers say farming is likely to stop on almost 800 farms immediately.
Zimbabwe's economy is already in crisis, blamed largely on President Mugabe's land-reform programme.
Militants loyal to the government have occupied an estimated 1,700 white-owned farms over the last 18 months, demanding that they be redistributed to landless blacks.
This, and the violence that has accompanied it, has meant that farming activities have been massively disrupted.
Food aid
The World Food Programme is due to begin a huge relief operation next month to feed over 500,000 Zimbabweans who face hunger or starvation.
But on Sunday, the Zimbabwean Government announced a ban on humanitarian agencies from distributing food aid saying groups were using it as a pretext to campaign for the opposition party.
Information Minister Jonathan Moyo told state media that where food aid distribution is needed, it would be done by the government.
Mr Moyo stressed his government would not allow strangers to interfere in the political affairs of the county.
Aid groups and political analysts have expressed concern that the government will use food aid to bolster votes in the presidential election.