KATHMANDU (AFP) - Nepal's prime minister declared three days of national mourning for the victims of a huge earthquake and thanked donors in an address to the nation on Tuesday.

"In memory of the Nepali and foreign brothers and sisters and elders and children who have lost their lives in this devastating earthquake, we have decided to observe three days of national mourning from today," said Sushil Koirala in a televised address.

Saturday's 7.8-magnitude quake is known to have killed more than 5,000 people.