Authorities said the Harkat-ul-Jihad Islami militant group had sent an email claiming responsibility for the blast that killed at least 10.
A powerful bomb placed in a briefcase outside the High Court in New Delhi killed at least nine people and injured 45 on Wednesday.
Three terrorist bomb attacks have killed at least 20 and injured scores of people in Mumbai, threatening to destabilise peace talks with Pakistan.
India’s most famous yoga guru began a mass fast to the death on Saturday to demand reforms including the death penalty for corrupt officials.
Hundreds of athletes arrived in New Delhi for the scandal-hit Commonwealth Games on Tuesday, setting their sights on winning medals.
The Commonwealth Games should never have been awarded to India, Australia’s Olympic chief said on Friday as more top athletes pulled out.
