There are now unofficial police curfews in townships, with people being picked up and beaten, and lists at borders of MDC members and journalists.
The Government has instructed state hospitals not to admit MDC victims.
One of Mr Mugabe's strongest critics, the Catholic Archbishop of Bulawayo, Pius Ncube, last week called on opponents of the Government not to be intimated.
"I am ready to stand in front," he said.
"We must be ready to stand, even in front of blazing guns. Starvation stalks our land and the Government does nothing."
Mr Coltart said: "This is no longer about the MDC and its political aspirations. We've had a total crop write-off in the south, where people were already living on the edge."
Zimbabwe was once the breadbasket of southern Africa, but this will be the sixth consecutive year of food shortages since Mr Mugabe launched his program of seizing white-owned farms for distribution to landless blacks.
The World Food Program is now giving food aid to 1.5 million people - nearly 10 per cent of Zimbabwe's population.
The authorities have attributed the low yields to the long-running drought. But critics blame the farm seizures for the sharp decline in agricultural production. Only 100 to 200 white farmers are left on their farms, compared with 4000 in 2000.
Most farms are now in the hands of "cellphone" farmers, ruling party cronies who coveted the farmhouses for weekend getaways and have no real interest in farming. But there is no doubt that southern Zimbabwe has suffered a severe drought this year.The state television service, ZBC, quoted Agriculture Minister Rugare Gumbo as saying..."