Condoling the loss of lives in the deadly blast that left at least 11 dead and over 60 injured, Patil wished speedy recovery to the victims. Singh, who is on two-day visit to Bangladesh, denounced the terror strike as a "cowardly act".
"I just heard the sad news from Delhi about the bomb blast. I am told that 10 people have been killed. This is cowardly act of terrorist nature. We will deal with it. We will never succumb to the pressure of terrorism," Singh in Dhaka.
He said "this is a long war in which all political parties, all the people of India have to stand united so that the scourge of terrorism is crushed". Singh said he has spoken to Home Minister P Chidambaram on the incident.
BJP and Left parties asked the Government to explain to the people whether there was any intelligence failure. BJP spokesperson Ravishankar Prasad described the incident as a "great pain, great agony and great distress."
"We outrightly condemn it. Why is the government not taking action? The incident has happened right in the heart of the capital, adjacent to India Gate and outside a gate of the Delhi High Court. There is no security and there is no intelligence beef-up," he said.
"Terrorists come with impunity and kill people with impunity," Prasad said. CPI(M) leader Sitaram Yechuri said that terrorists have struck around the anniversary of 9/11 attacks and 2008 Mumbai terror strike, which was a "very serious indication".
Referring to the May blast in the High Court parking and the July serial blasts in Mumbai, the CPI(M) Politburo said the perpetrators of these attacks have not yet been identified or apprehended.
"The failure of the government and the intelligence- security agencies is a matter of serious concern. It is imperative that the government take effective measures to identify and apprehend the people involved. Only this will assure the people of their security", it said.
CPI National Secretary D Raja said the party strongly condemns the blast and asked the government to explain why such terror attacks keep happening in the country.
"The government should initiate a thorough probe into the incident and they should say whether it was a failure of the intelligence agencies or failure of the policy adopted by it with regard to terror," he said.
In another statement, the CPI Central Secretariat said it was unfortunate that Delhi and Mumbai continue to be the target of terrorist outfits and asked the Government to take all steps to prevent such incidents in future.
Uttar Pradesh Chief Minister and BSP chief Mayawati termed the blast as "cowardly" act and urged the Centre to provide proper compensation and help to the victims.