By Adriana Barrera MEXICO CITY (Reuters) – Mexican Senate committees on Monday gave general approval to a draft energy bill allowing private investment in the world's No. 10 oil producer in what would be the biggest opening of the state-controlled sector in its 75-year history. The bill, unveiled by senators from the ruling Institutional Revolutionary Party (PRI) and opposition conservatives on Saturday, would let private firms partner with ailing state oil firm Pemex via profit-sharing, risk-sharing and service contracts as well as licenses. The revised draft was a positive surprise for many in the oil industry, and the government hopes it will help stem a decade-long slide in crude oil output. Mexico's peso rallied on Monday to a seven-week high.