The talks will not cover last week's deal for Chinese short video app TikTok to switch to US-controlled ownership.
The discussions also will not cover the next round of high-level trade talks to be held between Treasury Secretary Scott Bessent and Chinese Vice Premier He Lifeng ahead of a November 10 expiration of the two countries' tariff-reducing trade truce, the source said.
Instead, the talks on Thursday will focus on technical details related to trade issues already discussed in previous rounds of talks, said the source, who requested anonymity due to not being authorised to speak publicly on the matter.
Bessent and He agreed in Madrid last week on a framework deal to place TikTok's US operations under American-controlled ownership, and President Donald Trump is expected to sign an executive order on Thursday declaring that the TikTok deal meets requirements in a US law that Chinese ownership ends or the app shuts down in the US.
The Madrid talks, like previous rounds in Stockholm, London and Geneva, covered a variety of trade issues between the world's two largest economies, but there has been no reported progress on core irritants.
These include Chinese demands for US tariff reductions, and US complaints about dwindling Chinese purchases of US farm products and China's growing state-driven excess manufacturing capacity flooding the world with cheap exports.