Voicing concern over the 'very real threat' of nuclear weapons falling into the hands of terrorists, India on Tuesday sought strict controls over such arsenal by countries having established nuclear programmes, in an apparent reference to Pakistan.

External affairs minister Pranab Mukherjee said the challenges of terrorism and nuclear proliferation were inter-connected and 'alarming aspect' was the linkages that radical terror groups have forged with 'a few nuclear scientists'.

In an apparent reference to activities of Pakistan's disgraced scientist A Q Khan, he said it was well known how transfer of uranium enrichment technology, equipment and even weapon design has taken place 'clandestinely and flagrantly in our region'.

Addressing a seminar on Asian security, which will focus on emerging challenges in the region, he said the threat of nuclear proliferation has been a 'principal cause of concern in recent years'.

The concern, he said, was not limited to new states acquiring nuclear weapons capability but extends to the "very real threat of terrorist groups laying their hands on nuclear material and even fully-assembled nuclear weapons".

He pointed out that one of the concerns related to the "inability of states to sufficiently safeguard their nuclear material, technology and facilities against attempts to procure weapons of mass destruction-relevant items".

Another factor, he said, was the "deliberate and callous proliferation by states, including state failure, to exercise adequate control over personnel engaged in nuclear programmes".

Mukherjee said the challenge before the world community was to ensure that national laws and international commitments are "better implemented by states to prevent leakage of material and technology from established nuclear programmes without short-term considerations of political expediency".

Talking about dangers of nurturing terrorism as a 'political tool', the external affairs minister said it could recoil and "wound the state that wields it".

He noted that "terrorists have successfully used weakly-governed territories to organise attacks, recruit and train their cadres" which should 'not obscure the responsibility' of the countries concerned to prevent the misuse of their territories.

Citing Afghanistan under Taliban as a 'telling example', he said, "Continuing to allow these groups to enjoy the luxury of space will have terrible consequences for the world at large".

Mukherjeee said India does not wish to see the emergence of new nuclear weapon states, as it will endanger international security. But, later he clarified that the reference was not to Iran. He said as far as Teheran was concerned, New Delhi backed its moves to harness nuclear energy for peaceful purposes.