Non-resident company having establishment in connection with services and activity for another company when fabrication, positioning and upgradation activity started Rig undergoing necessary upgrades and repairs to meet another company requirements prior to agreement Rig already in contracting State for providing services in connection with exploitation, exploration or extraction of mineral oils Business income taxable in contracting State in which it arises Double Taxation Avoidance Agreement between India and Singapore, art. 51. On a writ petition contending that according to the Double Taxation Avoidance Agreement between India and Singapore the business profits of the Singapore enterprise could be taxed only if it had a permanent establishment in India and as the drilling operations in India were only undertaken for 119 days which was less than the threshold period of 183 days, accordingly, the assessee could not be said to have a permanent establishment in India.