People smoke marijuana on the informal cannabis holiday, 4/20, corresponding to the numerical figure widely recognized within the cannabis subculture as a symbol for all things marijuana, on the Common in Boston, Massachusetts, U.S., April 20, 2017. REUTERS/Brian Snyder

BOSTON (Reuters) - Massachusetts Governor Charlie Baker on Friday signed a bill raising the tax on retail sales of recreational marijuana to 20 percent, up from the 12 percent rate proposed in a successful 2016 ballot initiative.

The state is one of eight in the United States to have legalized use of the drug by adults 21 and older. Marijuana possession was legalized on Dec. 15, 2016, but retail sales of the drug remain illegal until Jan. 1, 2018, a delay intended to give state and local authorities time to decide how to regulate the trade.

Baker, a Republican, opposed legalization as did several senior state officials, and he voiced concern about the future after signing the law.

“I don’t support this. I worry terribly about what the consequences will be,” Baker told reporters. “We appreciate the careful consideration the legislature took to balance input from lawmakers, educators, public safety officials and public health professionals, while honoring the will of the voters regarding the adult use of marijuana.”

The law also allows cities and towns to ban or limit marijuana sales and creates a five-member Cannabis Control Commission with responsibility for overseeing the sale of recreational and medical marijuana.

The measure approved by voters called for legal retail sales of the drug to begin on July 1, but state legislators pushed that date back by six months to allow time to develop regulations. Legalization backers, who had protested the delay, called on state officials to move quickly in appointing the new control commission.

“The state will benefit greatly from the tax revenues and jobs created by the new industry, and we are confident lawmakers will secure appropriate funding to get the regulatory system up and running on the current timeline,” said Jim Borghesani, a spokesman for Regulate Mass, which supported the ballot initiative.