WALKERTON, Ontario, (UPI) -- A medical officer of health who first blew the whistle about Canada's worst-ever E.coli outbreak now says 2,000 people were infected, or twice the number originally reported. The outbreak, which hit Walkerton, Ontario, in mid-May, killed at least seven people and sent more than 50 to hospital for dialysis treatment.

Some 1,000 were originally reported to have visited emergency rooms after drinking contaminated water from the town's supply system, but Wednesday Dr Murray McQuigge said the number was more than 2,000. Investigators have since found that water from a well containing E.coli was pumped into the system for three days without chlorine being added, after the chlorination system broke down.

Walkerton, a community of 5,000, has since been drinking bottled water donated by people across the province, and officials say it may be at least eight weeks before the town's water supply system is declared safe again. Meanwhile, the tainted water scandal has been rocking the provincial government of Premier Mike Harris, who has been taking heavy criticism for cuts to his Environment Ministry after he came to power in 1995. Harris's conservative government is seen to be in jeopardy after the scandal.

n Ottawa. federal Environment Minister David Anderson also defended his policies in the House of Commons.

On Monday, Prime Minister Jean Chretien said his government would spend whatever was needed to make the water supply system safe across Canada. He pledged funding to municipalities that came up with environment-oriented infrastructure projects. The costs could run to billions of dollars.

Meanwhile, investigators trying to find the source of the E.coli contamination in Walkerton are now looking at livestock farms located uphill from the wells that supply the town's drinking water. Scientists believe that E.coli from cattle manure may have seeped deep into the soil and got into the underground water that feeds the wells.