US Trade Representative Demetrios Marantis said in an interview with CNBC that while the TPP seeks to eliminate trade barriers and require members to comply with a high standard of transparency, China has to meet the high standards if it wants to join the pact.

The unnamed source from the Ministry of Commerce said: "We know it's difficult, but the key point is we have to change minds and stick to opening-up to the world. Once we are determined on the TPP, everything else will be solved."

The source said ongoing talks on an investment treaty between China and the US will pave the way for China to join the TPP.

"The treaty touches on many sensitive and important issues, based on which talks on the TPP would be easier," he said.

China and the US began to negotiate on the investment treaty early in 1980, but the talks were suspended before being relaunched in 2008.

Yang Ziman in Beijing and Chen Weihua in Washington contributed to this story.