Sinopec gets nod to buy 20% of Russia's Sibur

China Petrochemical Corp, better known as Sinopec, has got the green light from the Russian government to buy a 20 percent stake in Russian petrochemical and gas company Sibur, a move that signals the petrochemical company's ambition to expand overseas.

The takeover involves two stages - Sinopec will acquire 10 percent of Sibur for about $1.34 billion then buy the other 10 percent within the next three years, according to Russian media reports.

Shares in Sinopec declined 0.4 percent to 4.9 yuan (76 cents) on Tuesday on the Shanghai Stock Exchange.