New Delhi: A war of words has broken out between India and the US over the sharing of critical information on the 2008 Mumbai attacks, just days ahead of US President Barack Obama’s visit to India on 6-9 November.

Upcoming visit: Barack Obama. AP

US ambassador to India, Timothy Roemer, told reporters on Wednesday that the US government has shared intelligence on a “regular" and “consistent" basis with the Indian government on the November 2008 Mumbai attacks in which 166 people, including six Americans, were killed by 10 Lashkar-e-Taiba gunmen during a 60-hour siege.

“We also shared information after the attacks," he said, describing the cooperation in counter terrorism as “historic and unprecedented" in nature.

When India asked for access to Pakistani-American David Coleman Headley, arrested in the US in October last year, Indian government investigators were allowed to question the man, Roemer said.

“We gave it (access) because India is our strategic partner and friend and somebody we share intelligence with on a regular basis," the US ambassador said.

Roemer’s remarks were in a response to home secretary G.K. Pillai’s remarks to the CNN-IBN news channel that India was “disappointed" with the information shared about Headley. “Yes, we could say that we were disappointed that the name of David Headley was not provided, if not pre-26/11 at least post-26/11. So that when he came subsequently in March 2009 to India at least at that time we could have nabbed him here," Pillai said.

These comments follow US media reports that two of Headley’s ex-wives had tipped off US investigators about his links with the Pakistan-based Lashkar-e-Taiba terrorist group that India and the US say carried out the Mumbai attacks.

After his arrest, Headley confessed to US investigators that he had aided the plotters of the Mumbai attacks by conducting reconnaissance of the locations and making video films of the targets during multiple visits to India. Officials of India’s home and foreign ministries have acknowledged that the government was able to unravel many significant strands of the Mumbai plot thanks to the technical assistance given by the US.

Counter-terrorism is one of the issues that both sides have often highlighted as an example of their close strategic partnership. A senior home ministry official said the Headley issue will not figure in talks during the Obama visit.

In a separate comment on India signing the Convention on Supplementary Compensation (CSC), a step that will enable India to engage in nuclear commerce, Roemer said acceding to the pact would help the country gain access to technology to produce electricity. “I think in terms of the signing, it recognises the benefits to India, to Indian suppliers, Indian industry and to the Indian people," he said of the convention that specifies the parameters on a nuclear operator’s financial liability. It provides for the establishment of an international fund to increase the amount available to compensate victims in the event of a nuclear accident and allows for compensating civil damage. India and the US concluded a landmark civil nuclear agreement two years ago that paved the way for the South Asian nation to access previously forbidden nuclear technology and buy atomic power plants from the international market without signing international non-proliferation pacts.

Sahil Makkar contributed to this story.