Some 60 firefighters and equipment left Cyprus on Tuesday for Greece, where more than 50 people have died in the fires, according to officials from the European Commission, the EU's executive arm.
Spain planned meanwhile to send two water-bomber Canadair planes to Greece, they added.
"Everything possible will be done to provide support today, tomorrow and for as long as it takes," European Commission President Jean-Claude Juncker said in a statement.
EU countries Spain, France, Germany, Italy, Portugal, Lithuania, Denmark, Poland and Austria have also responded to calls for help from Sweden, which was battling 21 active fires nationwide.
So far they have sent 340 firefighters, 60 vehicles, seven Canadair planes and seven helicopters.
READ MORE: Everything about Sweden's unprecedented heatwave
Fires have also hit Latvia, which is receiving assistance from the European satellite Copernicus, the commission said.
The eruption of fires across such a large swathe of Europe, from the far north to the south-east, is prompting appeals for the adoption of a 2017 commission proposal to establish an EU-wide disaster force.
But a European source told AFP the plan is blocked by a number of member states.
Under a system in place since 2001, Brussels coordinates volunteer aid contributions from member countries when it receives an emergency call from a country in need.
The commission proposed an EU protection force endowed with its own resources following the deaths of nearly 200 people in fires last year in Portugal, Italy, Spain and France.