"We do run the risk because of a lack of gas and oil that it is being replaced by coal produced in other European countries," Knibbe told Reuters in Davos on Wednesday.

"Geopolitically we understand the sanctions, but from a carbon footprint, that is not a good thing," Knibbe said.

Knibbe said the insurer had not yet decided on the new deadline for phasing out its coal investments.

World leaders gathered in Davos this week worried that market gyrations would disrupt the transition to green energy and that companies would fail to meet their goals to reach net zero in the coming decades. Some countries have already turned to coal to meet their energy needs.

NN Group, with roughly 200 billion euros in assets under management ($214 billion), is also making its definition of a company involved in coal stricter, Knibbe said, so that even those with small exposure could be subject to divestment.

Climate activists have long lobbied investors to back away from supporting the heavily polluting coal industry.

"We cannot engage on everything, but coal is high on our list as an engagement topic," Knibbe said, adding that the longer it takes to reduce carbon footprints, the more the insurance industry would have to charge for insurance.

"The longer it takes ... we will see the premiums increase," he said.

(Reporting by Jessica DiNapoli in Davos; Editing by Alexander Smith)

By Jessica DiNapoli