In March, 184 moderators sacked by Sama, a company contracted by Meta to review Facebook posts, brought a lawsuit claiming unfair dismissal and alleging that workers in Kenya were subjected to inhumane conditions, including forced labor and irregular pay.
A Kenyan court suspended the mass sacking in June and two months later allowed Meta and the moderators to pursue an out-of-court settlement.
"The looming court battle follows the collapse today of talks," UK-based legal activist firm Foxglove, which is supporting the case, said in a statement.
"The moderators informed the court that Meta and Sama made very little attempt to address core issues raised by the petitioners," it said, adding that they will also sue for contempt of court.
The talks — mediated by Kenya's former chief justice Willy Mutunga and an official from the labour ministry — were due to last for 21 days from August 23.
FILE - Civilians flee as security forces take aim at a hotel complex attacked by al-Shabab, in Nairob on Jan. 15, 2019. Facebook has failed to catch Islamic State group and al-Shabab extremist content in posts aimed at East Africa, according to a study released June 15, 2022.
The moderators' counsel, Mercy Mutemi, accused Meta and Sama of "buying time and not being genuine."
"We kept waiting for them to participate... only for them to keep asking for an extension of time and then come back every time to refuse to take accountability," Mutemi said in the Foxglove statement.
"As long as the respondents are serious in engaging, we are happy to engage," she added.
Meta — which also owns Instagram and WhatsApp — is yet to comment on Monday's announcement.
The company is facing two other legal cases in Kenya.
In 2022, a former South African employee of Sama, Daniel Motaung, filed a complaint in Kenya against Sama and Facebook.
Motaung alleged, among other things, poor working conditions and a lack of mental health support.
The Silicon Valley giant is also facing another complaint in Kenya, where a local NGO and two Ethiopian citizens have accused Meta of failing to act against online hate speech in Africa.
AFP is involved in a partnership with Meta providing fact-checking services in Asia-Pacific, Europe, the Middle East, Latin America and Africa.