BEIJING (AFP) - Twenty-five Canadian students were released from medical surveillance for swine flu in northeast China, local government sources said, according to state media early Thursday.

The students, released Wednesday, were put under observation at a hotel immediately after flying to Changchun, capital of Jilin province, on May 2 from Canada via Beijing, the official Xinhua news agency said.

The Jilin Provincial Publicity Department said they had displayed no influenza A(H1N1) symptoms, the report said.

One of the Canadian students, Martin Leroy Deslauriers, told AFP by phone earlier this week from the hotel that none of the students had any symptoms and they believed they were singled out by authorities in the city of Changchun for being Canadian.

Canada has one of the highest numbers of cases of the virus.

A group of Chinese nationals who had been stranded in swine flu-hit Mexico returned home on Wednesday and were immediately quarantined, the Shanghai government said.

All 119 passengers and crew on a government-chartered Boeing 777 were isolated after arriving at Shanghai's Pudong International Airport, a local government spokesman told AFP.

The only confirmed case in China so far has been in the southern territory of Hong Kong but officials in Beijing are taking extreme measures to stop influenza A(H1N1) making its way to the mainland.

China's health ministry said passengers on the mainland who were on the same flight as the Mexican man who tested positive in Hong Kong would be out of quarantine on Thursday if they displayed no flu-like symptoms, Xinhua said.

Meanwhile, some of the 136 Mexicans repatriated from China Wednesday spoke of "discrimination" by Chinese officials who feared they could be carriers of the swine flu virus despite showing no symptoms.