A field trial that would release genetically modified mosquitoes in the Florida Keys would not harm humans or the environment, according to documents released Friday by the Food and Drug Administration.

The agency’s Center for Veterinary Medicine released a preliminary finding that no significant impact would result from the trial of a method that aims to reduce populations of the mosquito that spreads dengue, chikungunya and the Zika virus among humans. The trial is proposed by the British biotech firm Oxitec. The Florida Keys Mosquito Control District wants to test Oxitec’s mosquitoes in a small neighborhood north of Key West.

The FDA needs to review public comments before deciding whether to approve the trial. But the tentative approval could make it easier to explore similar trials in the southeast or Puerto Rico, said Oxitec chief executive Hadyn Parry.

“Time is not on our side here, if you look at how Zika has been spreading in Brazil and other countries,” Parry said in a conference call with reporters. “The sooner we can start the trial, the sooner we show what we can do.”

Oxitec modifies Aedes aegypti mosquitoes with synthetic DNA to produce offspring that won’t survive outside a lab. Oxitec has conducted similar tests in Panama, Brazil and the Cayman Islands.

With or without the test, the district is looking for additional options to kill Aedes aegypti, which it considers a significant and expensive threat. In a statement, executive director Michael S. Doyle said the district needs to be proactive and the trial will need to determine how efficient Oxitec’s mosquitoes are at suppressing the local Aedes population.

“A small trial like this is designed to see if highly reducing the population is possible with this technology here in the Keys. If so, we will then look at larger trial areas,” Doyle said.

A residents’ group called the Florida Keys Environmental Coalition wants the district instead to try infecting mosquitoes with a bacteria that curbs their ability to transmit disease, arguing that Oxitec’s proposal is mostly marketing hype and won’t be subject to adequate federal oversight.

In an email Monday to the Associated Press, the coalition’s executive director, Barry Wray, questioned the ongoing costs Oxitec’s method might incur.

“Oxitec has exploited the fear surrounding Zika very effectively,” Wray wrote. “When you start looking at the quantity of mosquitoes they need to continuously provide, in order to keep problems under control, the numbers are astounding. So is the money required!”

Doyle said the district is investigating several technologies for eradicating Aedes mosquitoes, but those other methods take years to develop and Oxitec is furthest along.

Oxitec developed the mosquito in 2002 and has been testing it outdoors since 2009, Parry said. The Keys district approached Oxitec about trying its technology in 2010.

The company will cover the costs of the Keys trial, if it is approved, and a lab in the Keys town of Marathon, where the mosquitoes will be raised, has passed federal inspections. The company’s application allows for a trial of up to 22 months, but such tests elsewhere have reduced mosquito populations in about six months, Parry said.

Oxitec’s goal is to sell its mosquitoes and services in the way that other companies sell insecticides.

The Keys district spends more than $1 million a year to suppress up to half of its Aedes aegypti population. Oxitec’s method would not increase the district’s costs, but it would boost the area’s suppression rates up to 90 percent, Parry said.

Critics of genetic modification have criticized Oxitec’s trials. They say more proof is needed that stray female modified mosquitoes are not spreading genetic material through bites and that there are no other environmental risks, such as opening areas to infestation by another ­disease-carrying mosquito species.

— Associated Press