The UN chief also expressed "solidarity with the government and people of India".
The explosion occurred around 10.15 a.m. outside Delhi High Court where about 300 visitors were crowding Gate 5 for passes to enter the complex. Several people died instantly while others collapsed.
A statement issued from the UN chief's office said: "The secretary-general strongly condemns the bomb attack at the Indian High Court in New Delhi which has killed and injured many today.
"The secretary-general reiterates his firm stance that there is no justification for indiscriminate violence against civilians."
"The secretary-general extends his sincere condolences to the families of the victims and hopes that the perpetrators will be brought to justice," the statement added.
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