NEW DELHI, June 19 : Oil prices rose on Friday as the prospect of a lasting truce between the U.S. and Iran was clouded after peace talks in Switzerland were called off and as Israel stepped up attacks on Lebanon. By 0645 GMT, Brent crude futures gained 51 cents, or 0.64 per cent, to $80.36 a barrel, and U.S. West Texas Intermediate crude rose $1.28, or 1.7 per cent, to $77.88 a barrel, with the front-month July contract expiring on Monday. Both contracts were headed for a weekly loss of about