The planned acquisition of BG Group is one step closer to completion after clearing Australian anti-trust authorities, Royal Dutch Shell announced.

The Australian Competition and Consumer Commission cleared the proposed merger between the two energy giants.

"The Shell BG combination is a sign of Shell's confidence in the Australian economy," Shell Chief Executive Officer Ben van Beurden said in a statement. "It's also a springboard to change Shell into a simpler, more profitable and resilient company in a world where oil prices could remain low for some time."

The deal, valued at around $70 billion, is among the largest acquisitions since the Exxon Mobil merger was completed in 1999. It also comes at a time when most energy companies are streamlining capital expenses in a weak oil market.

Shell for the third quarter reported a $7.4 billion loss, compared with a $4.5 billion profit in third quarter 2014. BG Group moved along a similar trajectory, with revenue off 9.5 percent year-on-year.

The companies received unconditional approval for the merger from the European Commission in October. They still need the consent from the Chinese Ministry of Commerce and the Australian Foreign Investment Review Board.

The details of the proposed merger were announced in April. The companies say they expect the combination will be completed in early 2016.