G9 was set up in 2010 by nine offshore wind project developers, including Danish firm Dong Energy, UK-based Centrica and Sweden's Vattenfall. It aims to improve health and safety in the offshore industry.
The group's annual incident report shows there were 959 reported incidents in 2014 across 45 sites in Europe, compared to 616 a year earlier. The figures were compiled in association with the Energy Institute.
The increase in reported cases has been partly caused by a larger number of projects involved in the study. Last year, 35 sites took part.
An Energy Institute spokesperson said: "Unfortunately there is no straight answer to explain the increase.
"There are a larger number of sites being reported than last year, and some of these will be at different stages of development which may have higher risk attached ie. construction."
G9's biggest increase in reported cases was the number of "near hits" which leapt from 345 in 2013 to 655 this year – a 90% increase. A majority of the near hits occurred on the turbine or during onshore activities.
G9 defines a 'near hit' as "any incident which could have resulted in a work-related accident but did not, either by chance or timely intervention."
Breakdown of reported incidents 2014
There was also an increase in the number of incidents that needed first aid or medical treatment. This year, there were 149 reported cases that required medical care or first aid – up 63.7% year-on-year and 15.5% of the total number of incidents.
In 2013, 91 incidents required first aid or medical treatment making up 14.8% of the total incidents reported.
Encouragingly, however, for the second year running there were zero fatalities in the offshore industry and the number of work days lost due to incidents fell 33% to 44.
The spokesperson added: "The results from this do contribute to the development of the G9 research programme which has included providing good practice guidelines on topics such as working at height."