Fighting in Sudan abated overnight after the army and a rival paramilitary force agreed to a 72-hour truce, but a witness said gunfire could be heard on Tuesday while Arab, Asian and Western nations were racing to evacuate their citizens from the country.
US Secretary of State Anthony Blinken announced the agreement first and said it followed two days of intense negotiations. The two sides have not abided by several previous temporary truce deals.
A power struggle erupted between the SAF and Rapid Support Forces (RSF) paramilitary group on April 15 and has killed at least 427 people, knocked out hospitals and other services.
"During this period, the United States urges the SAF and RSF to immediately and fully uphold the ceasefire," Blinken said in a statement.
A Reuters witness said he heard gunfire from time to time in the city of Omdurman adjacent to the capital after a period of relative calm overnight.
The British government launched a large-scale evacuation of its nationals on military flights from an airfield north of Khartoum, open to those with British passports.
"We have started contacting nationals directly and providing routes for departure out of the country," Foreign Secretary James Cleverly said on Twitter.
All Japanese people who wished to leave Sudan have been evacuated, Prime Minister Fumio Kishida said on Tuesday.
The Swiss foreign minister said on Tuesday that Bern was monitoring opportunities to extract its remaining citizens but said it was having difficulty getting out people with dual nationality - the majority of the remaining Swiss in the country.
Switzerland has already shut its embassy and evacuated the staff and their families, and they arrived in Bern early on Tuesday morning.
Ahead of the evening truce announcement, air strikes and ground fighting shook Omdurman, one of three adjacent cities in the capital region, and there were also clashes in capital Khartoum, a Reuters reporter said.
Dark smoke enveloped the sky near the international airport in central Khartoum, near the army headquarters, and booms of artillery fir e rattled the surroundings.
UN Secretary-General Antonio Guterres said that the violence in a country that flanks the Red Sea, Horn of Africa and Sahel regions "risks a catastrophic conflagration ... that could engulf the whole region and beyond".
Tens of thousands of people, including Sudanese and citizens from neighbouring countries, have fled in the past few days to Egypt, Chad and South Sudan, despite instability and difficult living conditions there. Foreign governments have been working to bring their nationals to safety.
