By Katie Reilly

NEW YORK (Reuters) - New York has fined four makers of liquid nicotine used in electronic cigarettes over packaging that was too easy for children to open, in violation of a law enacted last year after a toddler died from ingesting the substance, the state's top prosecutor said on Tuesday.

New York Attorney General Eric Schneiderman announced a settlement with four companies selling liquid nicotine products online and in brick and mortar stores in New York.

The settlement requires the four companies to remove from New York stores all liquid nicotine with packaging that is not child-resistant. The companies must also pay penalties totaling $95,000 to the state and show proof of testing packaging for proper poison protection.

The first child in the United States to die from exposure to liquid nicotine was reportedly an 18-month-old boy in upstate New York who succumbed in 2014 after accidentally ingesting the toxic fluid.

Shortly thereafter, the New York Legislature passed a bill requiring that all liquid nicotine be sold in bottles that are more difficult for children to open. The bill was passed in June and signed into law in December.

The settlements are a result of an ongoing investigation to monitor compliance with the law.

"We are committed to protecting young people from the dangers of tobacco in all forms," Schneiderman said.

“As our investigation continues, I urge the federal government to do their part by requiring child-resistant packaging for these products nationwide, and to regulate the marketing and advertising of e-cigarettes,” he said.

Liquid nicotine is used in e-cigarettes, which are becoming increasingly popular among both adults and minors. E-cigarette use among middle and high school students in the United States tripled from 2013 to 2014, according to a recent report by the Centers for Disease Control and Prevention.

About 10 percent of U.S. adults now use e-cigarettes, according to an online Reuters/Ipsos poll of 5,679 Americans conducted between May 19 and June 4. That statistic is almost four times higher than an estimate by the U.S. government that 2.6 percent of adults used e-cigarettes in 2013. [IDn:L1N0YV128]

Three of the companies, Rocket Sheep, Henley Vaporium and ECig Distributors, Inc, were not immediately available or could not be reached for comment.

The fourth, Beyond Vape, posted a notice on its website offering customers who purchased liquid nicotine in New York after Dec. 29, 2014 a free child-resistant container of liquid nicotine or a full refund.

(Reporting by Katie Reilly; Editing by David Gregorio)