RIYADH: Oil prices rose slightly on Friday, but remained down on the week on fears that hefty interest rate increases will curb global economic growth and demand for fuel. Brent crude futures settled at $91.35 a barrel, up 51 cents, while US West Texas Intermediate crude futures settled at $85.11 a barrel, up one cent. Both benchmarks were down by nearly two percent on the week, hurt partly by the US dollar’s strong run, which makes oil more expensive for buyers using other currencies. India slashes taxes on aviation fuel exports, domestic crude oil The Indian government lowered taxes on aviation turbine fuel exports to 5 rupees per liter from 9 rupees per liter, a government notification said on Friday. The government also reduced windfall tax for domestically produced crude oil to 10,500 rupees per ton from 13,300 rupees per ton, according to the notification. US drillers add oil and gas rigs for first time in three weeks: Baker Hughes US energy firms this week added oil and natural gas rigs for the first time in three weeks, as relatively high crude prices encouraged some firms to drill more, mainly in the Permian Basin. The oil and gas rig count, an early indicator of future output, rose four to 763 in the week to Sept. 16, its highest since August, energy services firm Baker Hughes Co. said in its closely followed report on Friday. Baker Hughes said that puts the total rig count up 251, or 49 percent, over this time last year.