Chinese, French and Iranian energy giants signed a $4.8 billion deal to develop the world's largest natural gas reserve in the Persian Gulf on Monday.

The parties-China National Petroleum Corp, France's Total and the National Iranian Oil Co through its Petropars subsidiary - will develop the South Pars gas field, the first major energy investment since sanctions against Iran were lifted early last year. Production is to begin within 40 months, according to the agreement.

The French company will have a 50.1 percent interest, with CNPC owning 30 percent and Petropars 19.9 percent.