The South Caucasus region was shrouded in dust and sand, whipped up from Middle East and North African deserts on Wednesday.

Georgia was subjected to a muddy downpour in which the dust mixed with rain while Armenia and Azerbaijan battled dust clouds and fog.

The sandy rain fell in the Georgian capital of Tbilisi for well over two hours, leaving yellow spots and specs on everything from the clothes of pedestrians to motor vehicles and roads.

The slimy rain stuck to car windshields, making driving hazardous.

Meteorological experts said the rain posed no health risk to humans.

In the Armenian capital of Yerevan, health experts reassured the public the dust cloud covering the city all morning Wednesday was not dangerous to human health and would move away soon.

Karine Danielyan, an environmental protection specialist, and nuclear expert Ashot Martirosyan both denied rumours the cloud was caused by a blast at Armenia's Metsamor nuclear power plant.

"The nuclear power plant is working normally," Martirosyan said.

In Baku, the capital of Azerbaijan, civil aviation experts said there were no delays to aircraft movements caused by the hazy fog.