Nine defectors are in danger of being sent back to North Korea after being caught in Vietnam and handed over to China last month, an activist group said Tuesday. Among them are an army captain and a one-year-old boy.

After fleeing the North in early October, they traveled from Shenyang to the town of Nanning on the Chinese border with Vietnam, according to the Citizens' Alliance for North Korean Human Rights.

They crossed the border on Oct. 22 but were caught by Vietnamese police during a random check on a bus bound for Laos in Móng Cái, Vietnam. They were handed over to Chinese police in Dongxing, Guangxi, where they were detained until recently. On Monday they were taken to Shenyang by train and transferred to a garrison in the border town of Tumen and are now facing repatriation to the North.

"Despite diplomatic efforts to release them, we can't be optimistic," a government source here said.

China used to repatriate all defectors that were caught there, but since last year it has mostly stopped. Now there are worries that improving ties between the two allies mean defectors will be sent back again.

Bilateral relations worsened after North Korea's third nuclear test and execution of the pro-Beijing eminence grise Jang Song-taek in 2013.

But lately there have been signs that relations are improving. "China has been more generous to North Korean defectors not because of the Park Geun-hye administration's strong ties with China but more probably because of Beijing's dissatisfaction with the North," a diplomatic source said.

"But now that relations are improving, Beijing seems to be going back to its old policy as a gesture of goodwill toward Pyongyang."