The Queen has sent a message of sympathy to the Sierra Leone president following the devastating mudslides and flooding that have killed more than 300 people in the west African country.
The death toll is expected to rise after mudslides and floodwaters in and around the capital Freetown killed hundreds this week, many of whom were trapped as they slept.
More than 100 children are among the victims and the Red Cross estimates 600 people remain missing.
In her message, sent to President Ernest Bai Koroma, the Queen said: "Prince Philip and I were deeply saddened to learn of the terrible flooding and landslides in Freetown that have led to the deaths of so many people.
"Our thoughts and prayers are with all who have lost loved ones and those whose homes and livelihoods have been affected. Elizabeth R."
The president of Sierra Leone has declared seven days of mourning and reportedly appealed for support from other nations.
Authorities have said more than 300 people were killed in and around Freetown on Monday following heavy rains. Many were trapped under tons of mud as they slept.
Many of the impoverished areas of Sierra Leone's capital are close to sea level and have poor drainage systems, exacerbating flooding during the rainy season.
Freetown is also plagued by unregulated building of large residential houses in hilltop areas.
The Prince of Wales has also sent a message of support to the President of Sierra Leone, on behalf of himself and the Duchess of Cornwall, describing how the country is in their thoughts and prayers.
The message read: "My wife and I were so deeply shocked and saddened to hear of the dreadful loss of life and devastation caused by the recent flooding and mudslide in Freetown and we wanted you to know just how much our hearts go out to all those who have been so cruelly bereaved or injured, or whose homes have been destroyed.
"However inadequate this may be, I can only assure you that Sierra Leone is very much in our thoughts and prayers."
Charles held a private meeting with President Ernest Bai Koroma in London at a conference devoted to the West African republic in 2009, and three years earlier visited Sierra Leone to launch a project to help regenerate one of the most disadvantaged areas of the capital Freetown.