China National Petroleum Corp, the country's largest oil company, could pay up to $14.5 billion for 75 percent of Spanish oil major Repsol's Argentine unit YPF, sources said yesterday.

CNPC, the parent company of top Asian oil and gas firm PetroChina, and Repsol have begun talks, sources with knowledge of the matter said.

The sources, not authorized to speak publicly, said an offer from CNPC - which in 2007 failed twice to buy all of YPF's Latin American assets amid wrangling over terms - had yet to be put on paper or formally submitted.