A court in Thailand on Tuesday ordered the release of seven students who were arrested last month for distributing leaflets urging people to vote against a proposed new constitution in a referendum next month.

The Bangkok Military Court ordered their release because police have completed their investigation of the June 23 protest, said an observer for the legal aid group iLaw, Yingcheep Atchanont. They still face several charges pending prosecutors' acceptance of the case.

The Aug. 7 referendum is on a constitution drafted under the military government that took power in a May 2014 coup. Critics say the draft is undemocratic, but are constrained from campaigning against it by very restrictive laws that could send them to prison for 10 years.

Despite the threat, opposition to the draft charter has risen in recent weeks, with supporters of the civilian government that was ousted by the army taking a prominent role. The government has issued many threats against such critics but not acted consistently against them.