Oil prices rose on Tuesday for a second day on increasing concerns about tightening European supply after Russia, a key oil and natural gas supplier to the region, cut gas supply through a major pipeline. Brent crude futures for September settlement rose $1.66, or 1.6%, to $106.81 a barrel by 0618 GMT, extending a 1.9% gain in the previous day. U.S. West Texas Intermediate (WTI) crude futures for September delivery increased $1.47, or 1.5%, to $98.17 a barrel, having gained 2.1% on Monday. Russia tightened its gas squeeze on Europe on Monday as Gazprom (GAZP.MM) said supplies through the Nord Stream 1 pipeline to Germany would drop to just 20% of capacity. read more Russia's cut in supplies will leave countries unable to meet its goals to refill natural gas storage ahead of the winter demand period. Germany, Europe's biggest economy, faces potentially rationing gas to industry to keep its citizens warm during the winter months.