Plans by BP PLC (BP) to sell its 60% stake in Argentine crude producer Pan American Energy to a joint venture of China 's Cnooc Ltd. (0883.HK) and Argentine-owned Bridas Energy Holding Ltd. is at risk of collapse, Bloomberg News reported Friday on its website, citing a person with knowledge of the matter.

The proposed deal, valued at around $7.1 billion, is facing opposition from politicians and may not be completed by a November deadline on the accord.

BP spokesman Robert Wine said "deals of this scale take time to finalize with competition authorities.

"We are working with the other shareholders in PAE to secure competition approvals and complete the deal. We can confirm the deal has not yet closed as Argentine competition approvals remain outstanding, but we remain optimistic that these approvals will be granted in due course."

In an email, Cnooc spokesman Jiang Yongzhi said the company is "still waiting for the Argentine government and regulatory approvals.

"We will keep the market well informed of the progress," the spokesman said.

Pan American, which speaks on behalf of Bridas, said it could not comment on shareholder issues.

A spokesman for the Argentine Planning Ministry could not be reached for comment.