Leaders from China and Southeast Asian states called for a swift agreement on what could become the world’s largest trade block at a regional summit on Sunday, but new demands from India left officials scrambling to salvage progress even as Prime Minister Narendra Modi chose to remain silent on a possible deal at the meeting of the leaders here on Sunday.

Hopes of finalising the Asia-wide Regional Comprehensive Economic Partnership (RCEP), which is backed by China, have been thrown into doubt at the summit of the Association of Southeast Asian Nations (Asean) in Bangkok, Thailand.

Summit host Thailand said late on Sunday that the deal could be signed by February 2020. Thailand had earlier said it aimed to conclude the negotiations by the end of the year.

New impetus to reach the agreement has come from the US-China trade war, which has helped knock regional economic growth to its lowest in five years. “The early conclusion of RCEP negotiations will lay the foundation for East Asia’s economic integration,” said a statement from China’s foreign ministry after Premier Li Keqiang met Southeast Asian leaders.

But Indian Prime Minister Modi did not even mention the RCEP deal in his opening remarks at a meeting with Southeast Asian leaders and instead spoke only of reviewing the existing trade agreement between Asean and India.

Nor did Modi mention the trade block, whose 16 countries would account for a third of the global gross domestic product and nearly half the world’s population, in Twitter posts after meeting the Thai and Indonesian leaders.

An Indian foreign ministry official later told a media briefing, “Let’s take all the RCEP questions tomorrow.”

Southeast Asian countries had hoped at least a provisional agreement could be announced on Monday.

But India has been worried about a potential flood of Chinese imports. A person with knowledge of New Delhi’s negotiations said new demands were made last week “which are difficult to meet”.

Negotiators were meeting into the evening on Sunday to try to come to an agreement, Thai government spokeswoman Narumon Pinyosinwat told reporters on Sunday.