Beijing - Chinese rights activists voiced alarm on the Internet over rising discrimination against ethnic Uyghurs in the wake of a deadly attack at a Chinese train station that the government has blamed on "militants" from the western region of Xinjiang.

Top officials have noted mounting anxiety and resentment between the country's majority Han Chinese and Muslim Uyghurs from Xinjiang since an attack in the southwestern city of Kunming on March 1 left 29 people dead and injured about 140 others.

Online accounts describe growing intolerance toward Uighurs across China, ranging from evictions from apartments to taxi drivers refusing to pick them up.

Reuters reporters saw signs in restaurants and hotels in Kunming saying Uyghurs were unwelcome.

Rights activists have taken to social networks to decry the reported abuses and challenge the characterisation of Uyghurs as dangerous or extremist.

"Because of the Internet we can learn about the many instances of Uyghurs facing discrimination, from being unable to stay in hotels and having their street stalls chased away to being accused of being terrorists," prominent dissident Hu Jia said.

There is no evidence or even suspicion from official channels that Uyghur groups may be linked to the disappearance of a Malaysian Airlines flight over the weekend.

"This will only deepen ethnic misunderstanding and make Uyghurs' plight more difficult," said Li Fangping, a humann rights lawyer representing Uyghur scholar Ilham Tohti, who has championed Uyghur rights and is facing separatism charges.

The United States, European Union and international rights groups have demanded the release of Tohti.

Advocates of Tohti say he has challenged official versions of several incidents involving Uyghurs, including one in Tiananmen Square in October, that China says was its first major suicide attack. His case is a sign of the government's hardening stance on dissent in Xinjiang, where Uyghurs make up less than 50 percent of the population.