A bomb outside the high court in the Indian capital, Delhi, has killed 11 people and injured at least 61.
Prime Minister Manmohan Singh, who is on a visit to Dhaka, condemned the attack which happened on Wednesday morning.
The bomb was apparently placed in a case near the first security checkpoint at the court where people were queuing for passes.
Security officials say they are taking seriously an email sent by Harkat-ul Jihad al-Islami, an Islamic group based in Pakistan, claiming it carried out the attack.
The email reportedly demands that a man sentenced to death for involvement in an attack on the Indian parliament 10 years ago should not be hanged.
The US state department says Huji is a terrorist organisation with links to al-Qaeda. The group has been accused of carrying out attacks in India, Pakistan and Bangladesh.
In July, 26 people died in three explosions in Mumbai. The BBC reports both Delhi and Mumbai are on high alert.