The petition features on Downing Street's website.

It asks the prime minister to reject the bid and to replace the county council with a Cornish Assembly of democratically elected members.

The council said a single authority would save money, but six district councils, which would be scrapped if the bid is approved, dispute this.

Cornwall is among 16 short-listed to become a unitary authority.

A final decision will be made by the government later in the summer.