Pope Leo XIV expressed his "profound grief" on Monday over a deadly militant attack on a church in DR Congo's northeast, saying he was praying for the victims and their families.

Allied Democratic Forces (ADF) rebels raided a Catholic church in the town of Komanda, killing 43 people who had gathered for prayer, the United Nations and the Democratic Republic of Congo's military have said.

Nine children were among those killed.

"His Holiness Pope Leo XIV learned with consternation and profound grief about the attack perpetrated against the Bienheureuse-Anuarite parish in Komanda," wrote Cardinal Pietro Parolin, the Holy See's secretary of state, in a telegram to Congolese Archbishop Fulgence Muteba Mugalu.

'Blood of martyrs'

He said the new pope was joining the families of the victims and the Christian community in the region "in prayer."

"This tragedy invites us to work even harder for the integral human development of the scarred population of this region," said the telegram.

"His Holiness implores God that the blood of these martyrs may be a seed of peace, reconciliation, brotherhood and love for all the Congolese people."

The attack in Komanda ended a months-long period of relative calm in the Ituri region, which borders Uganda.

ADF kills thousands over the years

The ADF has killed thousands of civilians in the northeastern DRC.

Both the Ugandan and Congolese armies have sent troops to the region to tackle the militia.