A rights activist in Kazakhstan who faced seven years imprisonment over his outspoken opposition to neighbouring China was unexpectedly freed Friday as public and international pressure over his case mounted.

Serikjan Bilash, whose activism in defence of Muslim and Turkic minorities in Xinjiang earned him global media attention, told AFP he struck a plea bargain with the court that allowed him freedom but will end his activism.

"I had to end my activism against China. It was that or seven years in jail. I had no choice," Bilash told AFP at a restaurant where he held a celebratory midnight feast with his family and about 40 supporters.

Bilash agreed to accept guilt over inter-ethnic incitement charges triggered by his call for an "information Jihad" against the Chinese authorities over their policies in Xinjiang earlier this year.

He will also be unable to leave the city of Almaty - Kazakhstan's largest - for the next three months under the terms of his deal, he said, while noting he expected his supporters to continue taking the work of his informal Atajurt activist group forward.

"I had to do this for my family and my children," he told AFP as supporters in high spirits drank tea and ate a traditional meat-and-potato dish.

His release capped a dramatic night in Almaty, where some 200 hundred supporters surrounded the court where Bilash appeared and chanted for his freedom.

His lawyer Aiman Umarova had sounded the alarm earlier in the evening as she was unable to make contact with Bilash who had arrived at the courthouse before her and was immediately taken in by authorities.

Umarova refused to sign the plea bargain, insisting on her client's innocence, meaning Bilash had to find another lawyer to sign off on the deal.

"I refuse to put my name to any deal that was signed under pressure," Umarova told AFP.

Bilash had previously been held under house arrest after being detained and flown to the capital Nur-Sultan in March.

Critics connected his arrest to pressure from Kazakhstan's economically powerful neighbour.