The OPCW has been probing the chemical attack on a Russian ex-spy in the UK.
The allegations are part of an organised push-back against alleged Russian cyber attacks around the world.
Earlier, UK government accused the GRU of being behind four high-profile cyber-attacks whose targets included included firms in Russia and Ukraine; the US Democratic Party; and a small TV network in the UK.
Russia has called the accusations a "diabolical cocktail" of allegations.
‘Closed access hack’
The four suspects identified by Dutch officials had diplomatic passports and included an IT expert as well as support agents, officials said.
They hired a car and were seen to be scouting to carry out a closed access hack operation targeting the OPCW’s wifi network.
Equipment in the car boot was pointed at the OPCW and was being used to intercept login details, Maj Gen Onno Eichelsheim from the Dutch MIVD intelligence service said.