U.S. and Chinese officials described deputy-level talks that ended in Washington last week as "productive" and "constructive", but Chinese officials unexpectedly cancelled a visit to U.S. farms, denting investor sentiment.

Meanwhile, U.S. President Donald Trump reiterated that he wanted a complete trade deal, not just an agreement for China to buy more U.S. agricultural goods.

"Challenges to achieving a comprehensive deal remain, such as the issues of intellectual property and their enforcement, the amount of purchases by China and whether and when existing tariffs will be rolled back," analysts at Morgan Stanley said in a client note.

Thai shares slipped 0.8%, extending losses into a fourth session, on weakness in telecom and financial stocks. Kasikornbank Pcl and telco firm Intouch Holdings Pcl shed 1.2% and 5.5%, respectively.

Traders now await August manufacturing data, due on Tuesday, for further clues about the domestic economy. Manufacturing output likely dropped at a faster pace in August than in the previous month, a Reuters poll showed.

Singapore shares <.STI>, which are sensitive to trade developments, fell 0.5%, with financial and consumer stocks accounting for most of the losses.

Singapore Exchange dropped as much as 1.6% to a near three-week low following a rating downgrade by brokerage firm Jefferies, while DBS Group Holdings dipped 1%.

The city-state's core inflation gauge in August remained at a 3-year low, data showed, reinforcing expectations for policy easing this year.

Philippine shares <.PSI> fell as much as 0.6% before cutting losses on the back of financial and consumer stocks. The index closed lower for a fifth straight session, shedding 0.1% on Monday.

Investors now wait for a central bank policy meeting on Thursday, where Bangko Sentral ng Pilipinas is expected to cut interest rates for a third time this year, according to a Reuters poll, to support economic growth.

"Monetary stimulus is still very much expected but what people are looking for is for the Philippines to maintain an above 6% GDP growth strength, and that is key for foreign inflows," said Rachelle C Cruz, analyst at Manila-based AP Securities.

Vietnam stocks <.VNI> reversed course to drop 0.5%, dragged by financial and real estate names, while telecoms pushed the Indonesian index <.JKSE> 0.4% lower.

(Reporting by Shriya Ramakrishnan in Bengaluru; Editing by Subhranshu Sahu)

By Shriya Ramakrishnan