UNITED NATIONS, May 13 (Xinhua) -- UN Secretary-General Antonio Guterres on Sunday condemned the terrorist attacks on worshipers in three churches in Surabaya, Indonesia.

The UN chief was appalled at reports that children were used to participate in the attacks, said Guterres' spokesman Stephane Dujarric in a statement.

Guterres expressed his condolences to the families of the victims and wished a swift recovery to those injured.

He reiterated the support of the United Nations to the government and people of Indonesia in their efforts to fight and prevent terrorism and violent extremism, including through the promotion of pluralism, moderation and tolerance, said the statement.

A family of suicide bombers, including children, on Sunday carried out suicide attacks on the three churches in Surabaya that left seven people dead and dozens injured, said the police.