Islamabad doing own probe into allegations over terrorists' ties to Pakistan.
Pakistan was still awaiting "concrete proof" Saturday that a group based there carried out the devastating Mumbai attacks, as India said evidence was mounting and warned its anger had not cooled.
As twin bomb blasts killed 27 people in Pakistan's northwest, president Asif Ali Zardari stressed the country was also a victim of terror and was carrying out its own investigation into the assault on India's financial centre.
"Pakistan is currently doing its own internal investigation and is waiting for concrete proof to be handed over to us," Zardari told reporters in Istanbul, where he discussed ways to combat extremism with Afghan leader Hamid Karzai.
"Our position is that we have always been and still are the victims of terrorism," he said.
Last week's 60-hour Mumbai siege by 10 Islamic militants has badly hit relations between India and Pakistan, the nuclear-armed South Asian neighbours who have fought three wars since independence from Britain.
The attack by gunmen against multiple targets in Mumbai, including the landmark Taj Mahal hotel, killed 163 people including 26 foreigners. Nine militants were killed, while one was captured alive.
New Delhi has increasingly pointed the finger at Islamabad over the violence, sometimes referred to as 'India's 9/11', which has enraged public opinion and threatened a slow-moving peace process.
On Friday, prime minister Manmohan Singh said India has been angered "as never before" by the attacks as his new home minister hinted at growing evidence of Pakistani involvement.
"We have told the world that the people of India have felt a sense of hurt and anger as never before due to the Mumbai terror strikes," Singh said.
"It is the obligation of all concerned that perpetrators of this horrible crime are brought to book," Singh added.
India says all 10 gunmen involved in the assault came from Pakistan, and has handed Islamabad a list of 20 terror suspects, with demands for their arrest and extradition.
Suspicion has focused on Lashkar-e-Taiba, a Pakistan-based militant group which has fought Indian control of divided Kashmir. Lashkar was blamed for an attack on the Indian parliament in 2001, which pushed the two nations to the brink of war.
Indian home minister Palaniappan Chidambaram clearly had Pakistani groups in mind when he spoke of proof that elements outside the country were responsible.
"There is ample evidence to show that the source of the terrorist attack was clearly linked to organisations which have in the past been identified as being behind terrorist attacks in India," Chidambaram said.
"There are one or two countries which have broadly confirmed our preliminary conclusions," he added.
However, Chidambaram also acknowledged there had been some security and intelligence "lapses" prior to the attacks.
Several Indian newspapers on Friday cited unidentified intelligence sources as saying that Pakistan's powerful spy agency, the Inter Services Intelligence (ISI), was involved in training the gunmen.
The Indian Express said intercepts of conversations between the gunmen and their handlers showed the use of communication pathways often used by the ISI.
Separately Vienna officials said they would investigate reports the militants used an Austrian cellphone number during the siege.
The European Union also said it may increase aid to Pakistan and pledged to strengthen relations with Zardari's government to counter the threat of terrorism.
Pakistan has been a key US ally since the Sept. 11 attacks seven years ago, but many critics openly question whether elements in the Pakistan military and intelligence services support Islamist militants.
In the latest violence in Pakistan, at least 27 people were killed and dozens more wounded when two bomb blasts struck crowded markets in the northwest Friday as shoppers prepared for the Eid Muslim festival.