By Malini Menon and Gopal Sharma
NEW DELHI/KATHMANDU (Reuters) - Nepal and parts of northern India are battling their worst forest fires in years that have devastated thousands of hectares of woodland, killed at least 18 people and sent a pall of smoke across the southern Himalayas that can been seen from space.
In Nepal, 11 people have died while trying to fight fires that have razed 280,000 hectares (692,000 acres) of forest across the country, the worst in six years.
"This year we have experienced a longer spell of dry weather and the temperatures have risen significantly, contributing to the disaster," Forest Ministry official Krishna Prasad Acharya told Reuters.
The worst forest fires in four years in India's northern Uttarakhand state have killed at least seven people and disrupted the lives of thousands, an emergency official said on Monday.
The Uttarakhand fires have intensified in the past week, torching more than 2,000 hectares (4,900 acres) of forest.
Indian Air Force helicopters have been scooping and dumping water from reservoirs in an attempt to douse the flames, but operations were hampered by poor visibility.
A dozen locations, including in Almora, Pauri Garhwal and Chamoli districts, were badly hit, said Anil Shekhawat, a spokesman at the National Disaster Response Force.
"This can be compared with the worst fire of 2012," Indian Minister for Environment, Forests and Climate Change Prakash Javadekar said in New Delhi. Four people had been arrested on suspicion of starting forest fires, he added.
The number of reported forest fires has jumped to 1,689 so far this year in Uttarakhand, compared to 207 for the whole of 2015, according to data from the Forest Survey of India.
Forests cover about a quarter of India's total area.
"The fire is under control and has shown a downward trend in the past two days," said S. Ramaswamy, additional chief secretary of Uttarakhand.
India typically sees a rise in forest fires as temperatures rise from mid-March until the rainy season begins in June.
(Editing by Douglas Busvine and Nick Macfie)