India's ambitious project intending to study the properties of atmospheric neutrinos through an underground lab in Theni district of Tamil Nadu at a total cost of Rs 1,500 crore is awaiting a final nod from the Prime Minister's office.

"We have done all the pre-approval work such as fencing, constructing basic necessary buildings at Madurai. But the first step towards the main project needs PMO approval and that's what we have been waiting for," said Naba K Mondal, chief of India-based Neutrino Observatory (INO) project.

Mondal was here to present a paper on the INO project at the 80th annual meet of Indian Academy of Sciences, which concluded here yesterday.

Christened 'India-based Neutrino Observatory' by the Department of Atomic Energy, the project will study atmospheric neutrinos some 1,300 metres below ground near Pottipuram village of Theni district and is expected to provide precise measurement of neutrino mixing parameters.

INO was initially allotted Rs 83 crore to start various pre-project activities at the site.

The proposed INO comprises two underground laboratory caverns with a rock cover of more than 1000 metre all around to house detectors and control equipment, for which a two km access tunnel would be driven under a mountain, according to the INO website.

While the project was delayed in finding a site for itself, since earlier attempts were confronted by environmental issues. "We are already late by seven to eight years. If only we had started eight years back, we would have been in an advanced stage by now."

Recalling yesteryears when Indian scientists had the opportunity to use Kolar Gold Field mines for the study of neutrinos, Mondal said, they were planning to celebrate 50 years of studying atmospheric neutrinos next year.

More than 30 research institutions across India like Institute of Mathematical Sciences, Chennai, Tata Institute of Fundamental Research, Mumbai, Bhabha Atomic Research Centre, Mumbai, Saha Institute of Nuclear Physics, Kolkata, Indira Gandhi Centre for Atomic Research, Kalpakkam, Harish Chandra Research Institute, Allahabad and some IITs are coordinating with INO for the project.