Iran has sought help to fight a devastating fire in UNESCO-listed forests in its north, with neighbouring Turkey sending firefighting planes, Iran’s top environmental official said on Saturday.

The fire threatens the Hyrcanian forests, which stretch along the southern Caspian Sea coast and date back 50 million years. They are home to 3,200 plant species - a “floral biodiversity … remarkable at the global level”, according to UNESCO, which listed them as a World Heritage site in 2019.

“Two firefighting aircraft (and) one helicopter … are being dispatched by the Turkish government today. There is also the capacity to have cooperation from Russia if needed,” Vice-President Shina Ansari told state television.

Two Iranian Ilyushin firefighting aircraft, seven helicopters and about 400 firefighters are battling the blaze, which follows a drought marked by rain levels across Iran at 85% below average. The fire reignited last Saturday following media reports that it was put out after breaking out in late October.

Meanwhile, the head of a provincial nature protection unit said unauthorised hunters may have started the blaze and Reza Aflatouni, the head of Iran’s forestry body, suggested that the fire may be linked to illegal efforts to destroy forested areas in order to build private residences, according to Iranian media reports.