Illegal gold miners in Zimbabwe have seized a farm belonging to former first lady Grace Mugabe, local media reported, just four months after former President Robert Mugabe was ousted from power.

Hundreds of aggressive squatters have taken over portions of Grace's Smithfield estate in Mazowe, 25 miles north of Harare, and refused to move when she confronted them on Thursday.

"Undeterred by the presence of the miners, who were waving shovels and machetes at her, Grace told them to leave the property but they would not budge," the Daily News paper reported.

The casual miners uprooted citrus trees and dug tunnels on the property, vowing to remain there until Mrs Mugabe offered them work, the paper added.

"You no longer have any power to remove us," said one of the miners, quoted by the Daily News. "This is the new dispensation - and we do what we want."