LONDON (Reuters) - Oil prices rose on Monday after a key Middle East oil minister suggested the market was rebalancing, but investor sentiment remained under pressure from oversupply and concern over the prospects for global economic growth and fuel demand.Brent crude oil was up 90 cents a barrel, or 1.5 percent, at $61.18 per barrel by 1210 GMT. U.S. light crude was 65 cents higher at $51.85."Oil prices are regaining some ground on the back of bullish rhetoric from OPEC officials," said..