The US is moving more closely into line with Europe in restricting the use of neonicotinoid-based insecticides suspected of posing risks to bee populations.

Faced with mounting criticism as well as a still pending lawsuit - filed in 2013 by a coalition of beekeepers, environmental and consumer groups in a federal district court - the Environmental Protection Agency (EPA) has said it is unlikely to approve new or expanded uses of certain pesticides before the risks are fully evaluated.

The agency is currently conducting an assessment of six types of neonicotinoids and their impact on honey bees, with evaluation of four types expected by 2018 and the remaining two a year later.

Up to now, the EPA has not recognized the need for immediate action on neonics. The agency said early this month it would review its de facto moratorium if new crop protection problems appeared that could only be addressed by one of the pesticides in question.

 Last year, in what was believed to be the first broad-scale investigation of the insecticides in the US Midwest and one of the first in the country, the US Geological Survey (USGS) found that the use of neonics had "dramatically increased over the past decade, particularly in the farming states the Midwest. US environmental advocates say also that use is increasingly widespread the house and garden sector.

The EPA'S action came one day after the city commission of Portland, Oregon voted unanimously to suspend the use of the pesticides on its property over protests from farmers, nursery owners and others claiming the insecticide was crucial in combating pests.

At least eight other US municipalities are said to have banned neonics. 

The US Xerces Society for Invertebrate Conservation called the EPA's latest measure insufficient, as pesticides of this type currently in use also constitute "risks to our pollinators."

Over protests by agrochemicals giants including market leaders Syngenta and BayerCropScience, the European Union imposed a two-year moratorium on neonicotinoid pesticides effective Dec. 1, 2013.

In November 2014, Canada's Ontario province announced plans to reduce the acreage sown with crop seeds treated with neonicotinoid-based insecticides by 80% up to 2017.

Pesticide producers blame the bee disease known as Colony Collapse Disorder on a variety of factors, including habitat loss and disease, while disputing that neonics are the primary cause.