New Delhi, May 21 -- The Centre has told the Supreme Court it will permit no new hydroelectric projects in the upper reaches of the Ganga - the Alaknanda-Bhagirathi basin in Uttarakhand - and has rejected the recommendations of a court-appointed expert body that had cleared 28 such projects , although seven of these projects already commissioned or at an advanced stage of construction will be permitted to proceed. The upper Ganga basin is among the most ecologically volatile stretches of the Himalayas. Lying entirely within Seismic Zones IV and V, the Alaknanda-Bhagirathi system is the principal headstream of the Ganga - which sustains nearly half of India's population - and is prone to landslides, glacial lake outburst floods, avalanches, ...