Wildfires have been spreading across southern Europe, fuelled by the hot, dry climate.
Firefighters in Spain are struggling to cope with the country's worst blazes in a decade while thousands of acres of forest are being destroyed by fires spreading across Greece.
In Bosnia-Herzegovina, a state of emergency has been declared around a town in the northeast of the country, as fires have left many residents suffering heat exhaustion.
Fires believed to have been started intentionally have scorched 80 square kilometres 198 around the town of Castrocontrigo, miles (320km) northwest of Madrid.
Five hundred soldiers were deployed to help fight the fires, though no residents have yet been evacuated.
Satellite pictures showed huge plumes of smoke as flames cut across fields of pine trees.
Mayor of Castrocontrigo Aureliano Fernandez told Cadena SER radio that authorities believe the fire was started intentionally and the person responsible also tried to start one in the area last week.
Spanish authorities say 869 miles 1,400 square kilometres of woodland has been burnt by 11,000 wildfires since January 2012, most of which have been started deliberately.
The Greek secret service has been called in to investigate an unusually large number of fires that have spread across the country, to see if arson is to blame.
As officials announced the decision, more than 20 blazes raged out of control, including one that has ravaged the Aegean island of Chios for four days.
Boosted by gale-force winds, the blazes have already wiped out huge areas of forest and olive groves.
Almost 400 fire fighters, soldiers and volunteers were assisted by water-dropping planes and helicopters, the fire brigade said.
On Sunday, two French tourists were arrested on the Greek island of Andros on suspicion of arson, though prosecutors have yet to charge them with any offence.
Although forest fires are common during Greece's long hot summers, the country has seen hundreds of blazes in recent weeks following the heat wave.Bosnia-Herzogovina:
Authorities have declared a state of emergency around the town of Bratunac as a heatwave fuelled several wildfires leaving many residents suffering heat exhaustion.
Residents have teamed-up with forest rangers to prevent a blaze creeping towards the suburb of Slapasnica, while in the south of the country authorities fought four blazes which have raged around the town of Konjic for three weeks.
The battle to extinguish them has been complicated by the country's hilly terrain, strong winds and a 40 Celsius (104 Fahrenheit).
In Serbia, authorities have warned residents to stay inside and protect themselves from high temperatures.