PetroKazakhstan, a Canadian-listed company operating in Central Asia, said it had agreed to be bought by China National Petroleum Corporation (CNPC) for $4.18 billion, but rival ONGC said it had not given up hope, Reuters reported.
PetroKazakhstan has a rocky relationship with the Kazakh authorities and has fallen out with Russia's Lukoil, its partner in a joint venture in Kazakhstan.
State-run ONGC has sent the managing director of its overseas subsidiary to Moscow to hold talks.
