DES MOINES — Gov. Kim Reynolds has signed a bill into law that establishes a legal way to bet on professional, collegiate and international sporting events.

It also legalizes fantasy sports contests and internet fantasy sports betting but delays betting based on college sporting event statistics until May 2020.

The new law excludes betting on some events, including minor leagues and in-state college team players.

Sports betting is limited to those 21 and older.

Reynolds, a Republican, has declined to suggest whether she supported the expansion of gambling in Iowa. She signed the bill on Monday.

The law gives the Iowa Racing and Gaming Commission regulatory authority over sports betting. The commission regulates the 19 state-licensed casinos in Iowa and its administrator, Brian Ohorilko, has said most of the state’s casinos are expected to set aside onsite space for betting.

The casinos also will contract with online and mobile application vendors to set up bets electronically.

The commission has been developing rules that will determine how sports betting will work at the casinos, online and through a mobile application.

Betting is expected to begin as early as this summer.