“We will appeal and exercise every legal option we have to uphold state law and defend the rights and liberties afforded to any American citizen protected by our constitution,” Republican Governor Kim Reynolds said in a tweet on Monday night.

A federal judge had earlier ordered the state to immediately stop enforcing a law passed in May that prevents school boards from ordering the use of face masks, saying the law substantially increased the risks of catching the disease for children with health conditions.

The temporary restraining order will be in effect until the court orders a preliminary injunction.

Iowa has reported more than 450,000 cases of the coronavirus and over 6,300 deaths, according to a Reuters tally.

It joined a handful of other US states in May in passing a law that forbids cities, counties and local school districts from requiring people to wear face masks that protect against the spread of the coronavirus.

These governors have said that such rules of mask mandates infringe on personal liberty, while proponents of mask mandates say these are needed to combat surging cases, fuelled by the more contagious Delta variant, which has disrupted the reopening of schools across the country.

The US Food and Drug Administration, under pressure to approve a Covid-19 vaccine for children below 12, is meanwhile looking to complete a data review on the safety of children in clinical trials as quickly as possible.

Separately, Florida Governor Ron DeSantis has threatened fines for cities and counties that mandate employees must get vaccinated against Covid-19, which has killed nearly 50,000 people in the state.