Updated

Mexican President Enrique Pena Nieto has signed into law a sweeping reform bill that will allow private companies to drill for oil and gas.

Mexican law previously restricted such work to the state-owned oil company, Petroleos Mexicanos.

Pena Nieto said Friday that the energy bill and other reforms had strengthened confidence in Mexico, and cited as an example the decision by Standard & Poor's to raise Mexico's credit rating one step to BBB+.

Pena Nieto called the energy bill "a fundamental historic reform." Most private contracts had been banned since the oil industry was nationalized in 1938.

Congress must now pass enabling legislation in order for the law to enter full effect. Congress has three months to do so.