Russia’s full-scale invasion of Ukraine has triggered a significant rise in homelessness, according to a new report, with almost a quarter of those sleeping rough or in emergency shelters people who have had to flee from their homes.

The exact number of homeless people in Ukraine is not known, but the charity Depaul International surveyed more than 200 people living on the street or in emergency shelters.

The findings highlight the war’s profound toll on Ukraine’s civilians, with more than 3.5 million people internally displaced since the conflict started. Many of the 6.2 million Ukrainian refugees across Europe are also at risk of homelessness.

Anna Skoryk, the interim chief executive of Depaul Ukraine, told the Guardian: “Every day more people lose their homes because of occupation, shelling or because they’re close to the frontline. We cannot help everyone alone.”

The UN reported in February that 2m homes had been destroyed or damaged. Meanwhile, Russian forces continue to advance in eastern Ukraine, prompting the evacuation from Pokrovsk of about 20,000 people in the past month.

The British foreign secretary, David Lammy, warned at the Labour party conference in Liverpool on Sunday that the challenges posed by the war could deepen significantly over the next two years.

Of the homeless people interviewed by Depaul, 69% were men and nearly half were aged between 18 and 45. Former prisoners were also at particular risk, making up 31% of those interviewed.

Women and children receive more help – in the form of public shelters, international aid programmes and refuge abroad – than male citizens between 18 and 60, who are not allowed to leave Ukraine under wartime conscription laws.

There were fewer people aged over 45 on the streets because they were more likely to have medical conditions or would be less able to cope with Ukraine’s harsh winters – and more likely to be hospitalised or die, said Skoryk.

The growing number of homeless people has strained limited resources for society’s most vulnerable; there is only one government-administered homeless shelter in Kyiv serving central Ukraine.

Strict rules can lead to single men or those with addiction problems being turned away, and some shelters have been destroyed during the war. Temporary accommodation is available for people displaced by the war, but securing permanent housing poses significant challenges.

Skoryk, who lost her own home in Kharkiv when it was hit by a missile during the early months of the war, cautioned that even after the conflict was over, the problem of war-driven homelessness would persist for years.

As the war approaches its third year, support for the 6 million Ukrainians living as refugees abroad has also dwindled and many are at risk of homelessness.

In Hungary, the government recently ended housing assistance for thousands of Ukrainian refugees, designating certain western areas of Ukraine as “safe” to return to despite ongoing missile strikes.

In the UK, more than 9,000 Ukrainian refugee households have been put at risk of homelessness due to a reduction in the number of hosts offering accommodation and inadequate local authority support. Reports from across Europe also indicate refugees face bureaucratic hurdles that prevent them from accessing protections and assistance guaranteed under EU laws.

In Poland, which initially welcomed nearly a million Ukrainian refugees, public sentiment has shifted due to concerns about social benefits. This month, the country called for an end to EU benefits for men of fighting age, saying it encouraged draft dodgers in Ukraine.

The psychological toll of this uncertainty is profound. Depaul is urging a shift in how homeless and displaced populations are treated, emphasising the need for collaboration between the government, charities and other organisations to find permanent housing solutions and assist with other issues, such as medical support.

“Every person has the right to a place they can call home,” said Skoryk.