Authorities in the United States have issued the first ever fines for parents refusing to vaccinate their children amid a measles outbreak.

There have been 329 cases of the disease in New York since the outbreak began last October, though it is unclear how many cases are current, reports ABC News.

The city's health department announced that the three non-vaccinated people failed to comply with the Commissioner's Emergency Order mandating measles vaccination.

The department reports that 44 additional cases were added since last week’s emergency order.

They’re now facing fines of $1,000 ($1400 AUD).

Parents refusing to vaccinate their children against the measles virus are facing fines amid an outbreak in New York. (iStock)

To stop the spread of the virus New York officials ordered adults and children aged six months and older who live, work or go to school in four Brooklyn postal codes to receive the vaccine within 48 hours.

Four more schools have been shut down for failing to comply with mandatory vaccine orders.

ABC reports "disease detectives" are investigating cases of unvaccinated children. The cases will go to a hearing, where the parent will be fined.

Failing to appear at the hearing or respond to the summons will result in a $2,000 ($2800 AUD) fine.

Parents refusing to vaccinate their children against the measles virus are facing fines amid an outbreak in New York. (AAP)

The city is struggling to contain the outbreak, which is centered in ultra-Orthodox Jewish neighbourhoods in Brooklyn.

Health Commissioner Dr. Oxiris Barbot told Fox News: "Because of measles’ long incubation period, we know this outbreak will get worse before it gets better.

"However, we can turn the tide by people getting vaccinated, especially before Passover when families and communities will gather. We urge everyone to protect their children and their fellow New Yorkers by getting vaccinated immediately."