A large scale evacuation of Britons has begun in Sudan as warring parties — for the first time — honour the ceasefire agreement recently brokered by the US and Saudi Arabia.

Military flights would depart from an airfield outside Khartoum and would be open to British passport holders.

Prime minister Rishi Sunak has said “The Government has begun a large-scale evacuation of British passport holders from Sudan on RAF flights. Priority will be given to the most vulnerable, including families with children and the elderly.”

The British government said people will be contacted directly and should not go to the airfield unless they are called.

Foreign Secretary James Cleverly said the government had begun contacting nationals directly and providing routes out of the country.

On Monday, the government estimated that around 4,000 British nationals were in Sudan, and armed forces minister James Heappey said there was a military team in the country’s east conducting reconnaissance on possible options for assisting Britons to leave.

Integrity News reported that warring parties in Sudan reached a ceasefire agreement brokered by Saudi Arabia and the United States.

The Sudan Armed Forced and the Paramilitary Rapid Support Forces, RSF, confirmed the truce.

The United Nations has appealed to the Security Council to use their influence to prevail on the situation in Sudan and bring the country back to order.

More than 427 people have been killed while several other were confirmed injured in the two weeks old conflict.

Meanwhile, the World Health Organization (WHO) representative in Sudan has raised concerns about what has been described as “high risk” of a biological hazard on Tuesday, after one of the sides in the conflict seized a laboratory.

No further information was given by Nima Saeed Abid, according to Reuters, although reports have alleged that the Rapid Support Force had taken control of a lab.