Facebook and Intel have become the latest big tech firms to announce they are withdrawing from MWC in Barcelona, citing concerns about coronavirus.
Spanish media is reporting that trade body the GSMA, which organises MWC, will meet to decide whether to cancel the event entirely on Friday.
The GSMA declined to comment on “internal meetings”.
Amazon, Sony, LG Electronics, Ericsson and US chip company Nvidia have already pulled out.
Other big brands have told the BBC they are reviewing their plans.
Facebook said “evolving public health risks” were behind its decision.
So far the GSMA has said MWC will still go ahead.
However, one contact in the telecoms sector told the BBC that today was likely to be “a decisive day” for other firms contemplating dropping out.
More than 100,000 people usually attend Mobile World Congress every year, and thousands of firms exhibit. Around 6,000 people travel from China, according to GSMA figures.
In its latest statement, it said more than 2,800 exhibitors were still planning to take part.
Intel explained its decision to pull out: “The safety and wellbeing of all our employees and partners is our top priority, and we have withdrawn from this year’s Mobile World Congress out of an abundance of caution.”
Huawei said it was still planning to go but was reviewing the situation “on a daily basis”. The BBC understands it will be relying heavily on its western-Europe-based staff, rather than sending over many executives from Shenzhen.