Image copyright AP Image caption The pro-legalisation campaign spent millions on advertising

Voters in the US state of Ohio have rejected proposals to make marijuana legal, according to local media projections.

The measure, known as Issue 3, would have amended the state constitution to legalise the personal and medical use of marijuana for anyone over 21.

But it was defeated by nearly a two-to-one margin, the projections said.

Pro-legalisation campaigners spent about $12m in advertising in the run-up to Tuesday's vote.

Issue 3 would have granted rights for marijuana to be grown commercially at 10 sites across Ohio, which critics said could have created a monopoly.

The backers of the 10 growing sites had many famous names as investors, including former pop singer Nick Lachey, fashion designer Nanette Lepore and Woody Taft, a descendant of President William Howard Taft.

The legalisation measure would have allowed marijuana, pot-infused sweets and other related products to be purchased in stores. Home-growers could keep up to four flowering marijuana plants.

Image copyright AP Image caption Opponents of legalisation said they feared a monopoly

There was strong opposition to the measure from children's hospitals, business organisations and farmers.

Colorado, Washington, Oregon and Alaska, along with the District of Columbia, have legalised recreational marijuana.

More than 20 states permit its use for medical purposes.