Air raids by the Syrian government and its allies in the country’s last rebel-held enclave have killed more than 100 civilians in the past 10 days, according to the United Nations, which said the three-month campaign has displaced more than 400,000 people.

The 103 dead from the recent air attacks on schools, hospitals, markets and bakeries included at least 26 children, UN human rights chief Michelle Bachelet said on Friday, adding that the rising toll had been met with “apparent international indifference”.

The targets of the attacks were “civilian objects, and it seems highly unlikely, given the persistent pattern of such attacks, that they are all being hit by accident,” she said in a statement.

Backed by its main ally, Russia, the Syrian government began its offensive against the rebel enclave in northwest Syria – the last area of active opposition to President Bashar al-Assad – at the end of April, saying it was responding to violations of a ceasefire.

Since then, “more than 400,000 people have been displaced,” David Swanson, spokesman for the UN office for the coordination of humanitarian affairs (OCHA), said on Friday.

The region under attack is home to some three million people, nearly half of them already displaced from other parts of the war-ravaged country. It covers nearly all of Idlib province and parts of neighbouring Aleppo, Hama, and Latakia provinces.

Idlib and surrounding areas of the northwest were included in a “de-escalation” deal in September between Russia and Turkey, which backs some rebel groups, to reduce warfare and bombardment.

However, the accord was never fully implemented after fighters refused to withdraw from a planned buffer zone. Instead, the bombardment increased in intensity in recent weeks.

The region is mostly controlled by Hay’et Tahrir al-Sham, led by al-Qaeda‘s former Syria affiliate.

The Syrian Observatory for Human Rights, a Britain-based war monitor, has said more than 730 civilians have been killed in aerial bombardment and shelling of the region by the Syrian government and its allies since the end of April.

In Friday’s statement, Bachelet put the number of civilians killed since the start of the campaign at at least 450.

‘Deadliest days’

In a statement on Thursday, OCHA described Monday as one of the “deadliest days” in the region since the start of the flare-up, with 60 people killed in Idlib, Hama and Aleppo provinces, including 39 in an air raid in a busy market in Maarat al-Numan.

It also said that most of the displacement was from southern Idlib and northern Hama, the two areas that have been hit hardest by the flare-up.

“The majority of those fleeing have displaced within Idlib governorate while a smaller number have moved into northern Aleppo governorate. Roughly two-thirds of people displaced are staying outside camps,” it said.

The agency said it had documented 39 attacks against health facilities or medical workers in the region since the end of April. At least 50 schools have been damaged by air raids and shelling, it added.

Both the Syrian government and its Russian ally, whose airpower has been critical to Damascus’ military gains in recent years, deny targeting civilians or civilian infrastructure.