|This is the second blast at the Delhi court in less than a year [AFP]
A bomb apparently hidden in a suitcase has exploded outside the high court in New Delhi, India's capital, killing at least 11 people and wounding 45 others, officials said.
"This is a cowardly act of a terrorist nature," said Manmohan Singh, India's prime minister, who is currently on a visit to Bangladesh.
"We will never succumb to the pressure of terrorism. This is a long war in which all political parties, all the the people of India, have to stand united so that this scourge of terrorism is crushed."
Addressing parliament on Wednesday, Palaniappan Chidambaram, the country's interior minister, said: "We are determined to track down the perpetrators of this horrific crime and bring them to justice."
Delhi police released the sketches of two suspects hours after the bombing.
Authorities said the outlawed Harkat-ul-Jihad Islami (HUJI) group, with bases in Bangladesh and Pakistan, had sent an email claiming responsibility for the attack, the Reuters news agency reported.
"That mail has to be looked at very seriously because HUJI is a very prominent terrorist group among whose targets India is one," SC Sinha, National Investigation Agency (NIA) chief, told reporters.
In an email to the NIA, the group called on India to repeal the death sentence of a man convicted in connection with an attack on the Indian parliament in 2001 who was awaiting execution by hanging.
Police cordoned off the area, not far from parliament and the prime minister's office.
The attack was carried out even though the capital had been on high alert because parliament was in session.
The blast erupted near a large crowd of people waiting in line to reach a reception counter where passes are made for entry to the court building, RK Singh, home secretary, said.
"It appears that the bomb was in a suitcase because we have the remains of that suitcase," he told a local TV channel.
The state government in Delhi has announced compensation of Rs 400,000 [$8671.14] to the next of kin of those killed and Rs 100,000-200,000 [$2168-4336] for those injured.
People ran to the blast site to assist the injured, piling them into auto-rickshaws to take them to the hospital.
Fire engines and ambulances were also sent to the scene.
Forensic teams along with sniffer dogs and a bomb disposal unit were apparently checking for any further explosives.
Sanjay Kumar, a police official, said the court building was evacuated after the blast.
According to local news channels, the blast took place just before the court opened for hearings at about 10:am local time [4:30 GMT].
The explosion shook the courthouse, sending lawyers and judges fleeing outside, Sanjiv Narula, a lawyer who was in the building, said.
"There was smoke everywhere. People were running. People were shouting. There was blood everywhere. It was very, very scary," Sangeeta Sondhi, another lawyer, said.
Television images showed scores of lawyers in black coats running from one of the main gates of the building.
The blast in the heart of the capital will renew concern about the authorities' ability to prevent attacks, particularly in sensitive, high-risk areas.
"This is a glaring example of the shortage of intelligence, both human and technical," Ajai Sahni, executive director at the Institute for Conflict Management in New Delhi, said.
In May, a low-intensity blast outside the same court triggered panic but injured no one. The explosion on Wednesday was outside the busiest gate of the high court.
The blast was the first major attack in India since a string of bombs exploded in three busy Mumbai neighbourhoods on July 13, killing 24 people.