CNOOC and Unocal of California are expected to begin negotiations in the US on Monday on the Chinese-owned company's US$20bn takeover bid for the US energy group, the Financial Times reported Monday, citing business sources. Unocal had earlier accepted an offer from US Chevron for US$18 billion in stocks and cash, but it reopened negotiations for the higher bid. The two parties will discuss the bid documents sent by CNOOC that might be declared a superior offer