'While there is a great deal of external inspiration and support, we are looking at a mastermind within the country,' National Security adviser M.K. Narayanan told The Straits Times in an interview.

'Clearly, there is some kind of organisation. We have to find out if that organisation is localised or there is an external group or module operating,' he said, declining to be drawn into specifics.

A high-intensity surveillance operation that started in 2004 has helped Indian intelligence bust hundreds of terror modules across India.

But as most of the cells involve Muslims, the government has been careful about advertising its success, fearing it would lead to a backlash against the minority community.

Even so, dozens more terror groups have evaded detection.

Terrorists have targeted the tourist city of Jaipur, the technology hub of Bangalore, and Ahmedabad, a manufacturing centre.

In Ahmedabad, the bombers waited for the injured to be brought to hospital before setting off an explosion at the facility, looking to maximise the carnage.

Dozens of bombs were also defused the same week in Surat, a centre for the diamond trade.

Also last month, a suicide bomber targeted the Indian embassy in Kabul, killing the Indian defence adviser, another senior diplomat and more than 50 innocent people.

While India and US administration officials have blamed Pakistan's Inter-Services Intelligence (ISI) for instigating the Kabul blast, New Delhi has been silent on the domestic attacks.

Mr Narayanan suggested that local militant elements may be in touch with international terrorist groups.

'One of the things we had hoped would not occur was that of local elements getting sucked into worldwide movement of Al-Qaeda and terroristrelated activity,' he said. 'But if you look at the nature of the blasts, there are a great deal of complementarities in terms of triggering devices, nature of explosives and casings used.

'All this indicates much more high-grade people are involved in this effort.'

On the Kabul embassy attack, which he has blamed on the ISI, Mr Narayanan said the motive was to keep India from expanding its influence in Afghanistan.

'Pakistan wishes to be the only country (of influence) there so it can have Afghanistan as its client state. That is something not only India but the rest of the world is not prepared for.'

Some analysts think New Delhi may consider putting its troops down on the ground in Afghanistan.

But Mr Narayanan said that while India would beef up its security 'very substantially', it would not send in troops.

'We will not send our troops to any part of the world except for peacekeeping operations under the UN,' he said.

After Kabul, he said, India expected the government in Islamabad to take 'some action' against the ISI, or rogue elements within it.

'In any democratic country if an agency functions out of step with the political leadership, the agency head or operational chief suffers,' he said.

'But I am not sure if that will happen in Pakistan.'

New Delhi also was deeply worried about the political crisis in Pakistan, where President Pervez Musharraf is likely to face impeachment proceedings.

'Whether he is impeached is not important from the Indian viewpoint.

'But it leaves a big vacuum and we are deeply concerned because it leaves the radical extremist outfits free to do what they like, not merely on the Pakistan-Afghanistan border but clearly, our side of the border too.'

velloor@sph.com.sg