Dalton McGuinty's Liberals will introduce a provincewide ban of household pesticides if they are re-elected in October, CBC News has learned.

Sources said the pledge will be part of the party's election platform, which is expected to be released next week as parties kick off their campaigns for the Oct. 10 Ontario election.

Citing potential health risks, 25 municipalities across the province, including Toronto and London, have banned the cosmetic use of chemicals that kill bugs and weeds.

In those municipalities, homeowners and commercial companies can no longer use the pesticides for cosmetic use on lawns and gardens.

The Liberals' ban would be a similar public health-motivated measure as a previous provincewide ban introduced on smoking in public places such as bars and restaurants.

While the ban would cover all municipalities, towns and cities in the province, it would not affect farmers' use of pesticides and herbicides in their fields.