The head of the World Health Organization has called for an immediate ceasefire in the eastern Democratic Republic of the Congo to help tackle the Ebola outbreak there, as Uganda closed its border with its neighbour in an effort to stop the spread.

Tedros Adhanom Ghebreyesus posted on social media that the region was in the midst of a “catastrophic collision of disease and conflict with the Ebola outbreak in Ituri province outpacing the response”. Tedros said on Monday that he would travel to the DRC this week.

The number of suspected cases in eastern DRC is nearing 1,000, with at least 220 suspected deaths. The country’s health ministry said on Tuesday that 101 cases had been confirmed, and it was looking into more than 3,000 possible contacts.

In Uganda there seven confirmed cases and one death as of Sunday, WHO data showed.

Aid group Save the Children said on Wednesday that a quarter of the confirmed deaths were children, calling for infection prevention measures to be urgently scaled up.

Aid groups are rushing staff and equipment to eastern DRC but attacks on medics due to community distrust have hampered efforts, they say.

The outbreak was confirmed on 15 May in Ituri, the DRC’s most north-eastern province, which borders South Sudan and Uganda.

Diana Atwine, a senior Ugandan health official, told a press conference on Wednesday that Uganda’s border would be closed for four weeks, except to Ebola response teams, humanitarian and security operations and food and cargo transport.

Any person who was authorised to enter Uganda from the DRC would be required to undergo mandatory self-isolation for 21 days, she said.

The UN refugee agency said transit and reception sites in Uganda’s West Nile region –which borders the DRC – were at more than double capacity, a document showed.

Earlier this month, the WHO advised countries against closing their borders, saying it would push people to use informal border crossings, making it harder to monitor and stop the spread of the disease.

Eastern DRC has a number of armed groups. Though the government still largely controls Ituri, insecurity had been worsening there before the Ebola outbreak. Almost 1 million people in the province have been displaced by conflict, according to the UN humanitarian office.

The outbreak has spread south to rebel-held areas of North Kivu and South Kivu provinces, where the Rwandan-backed M23 group controls large swathes of the region.

Tedros said: “Stopping this Ebola transmission depends entirely on humanitarian access. Yet ongoing clashes are driving mass displacement, pushing exposed contacts into overcrowded camps and severing critical containment corridors.

“Frontline workers are risking everything, while attacks on health facilities make tracking cases and their contacts nearly impossible. We cannot build community trust or isolate the sick while bombs are falling. We urge all warring parties to agree to an immediate ceasefire to contain this outbreak.”

A doctor in Butembo, North Kivu – where there have been six deaths out of seven cases of Ebola – told Reuters they had only two body bags left, amid shortages of equipment.

“If there are more deaths I don’t know how we will manage,” the doctor said on condition of anonymity due to concerns it could impact their employment.

“We recently had to secure a body - we had no choice but to use our own money to buy a body bag.”

The doctor also reported critical shortages of soap, chlorine and personal protective gear including boots, body suits, masks and gloves, and said foreign aid cuts to international and local NGOs were partly to blame.

The response to the outbreak has been complicated by the transient nature of many communities in Ituri, where goldmines attract migrant workers, as well as by international aid cuts.

Philippe Guiton, the DRC director of the aid organisation World Vision, said: “For children, the risks are especially acute. Years of conflict have weakened community systems, and acute malnutrition has left many young bodies too fragile to withstand a virus as aggressive as Ebola.”

The response has also been hindered by attacks on health facilities by people wanting authorities to release Ebola victims’ bodies for burial.

Traditionally, burials involve families washing and touching the body. However, the bodies of Ebola victims are highly contagious and have been a key vector for spreading the disease in previous outbreaks in the region.

On Saturday and Sunday, people attacked a hospital in Mongbwalu, in Ituri. Its medical director, Dr Richard Lokodu, told Reuters that 18 Ebola patients fled the facility on Saturday when “unidentified individuals” burned tents where patients were being isolated.

On Sunday, seven more patients fled and an individual suspected of having Ebola died haemorrhaging in the attempt, he said.

In Uganda, all seven confirmed cases were reported in Kampala, the WHO said. They included a driver who had transported another case; a Congolese woman who had travelled to Uganda for medical care; a Congolese health worker who worked with other Congolese people seeking healthcare in Uganda; and two Ugandan health workers who had cared for an Ebola patient.

Reuters and Associated Press contributed to this report.