China's security ministry said Saturday that 109 Uighurs repatriated by Thailand had been on their way to Turkey, Syria or Iraq "to join jihad", state media reported.
Beijing also criticised the US State Department over its condemnation of Thailand's deportation of the Uighurs to China where it said "they could face harsh treatment".
Thailand on Thursday said it had deported some 100 Uighurs detained in the country after finding "clear evidence" they were Chinese nationals.
The deportations triggered condemnation from rights groups and fresh protests in Turkey over China's treatment of the Turkic-speaking, largely Muslim Uighurs in the northwestern Xinjiang region.
China's ministry of public security said Saturday 13 of the 109 repatriated had fled China after being implicated in "terrorist activities", the official Xinhua news agency reported.
It said many of them had been radicalised by materials released by the East Turkestan Islamic Movement (ETIM) and the World Uygur Congress.
The ministry also claimed a Chinese police investigation had uncovered several jihad recruitment gangs in Turkey, the Xinhua report said.
Citing accounts by returnees, the ministry said that after arriving in Turkey, "many" recruits, led by the ETIM, went on to fight in Syria.
Scores of Uighurs are believed to have fled restive Xinjiang in recent years, sometimes travelling through Southeast Asia in hope of resettling in Turkey.
China regularly accuses what it says are exiled Uighur separatist groups such as the ETIM of being behind attacks in Xinjiang, which has seen a wave of deadly unrest.
But overseas experts doubt the strength of the groups and their links to global terrorism, with some saying China exaggerates the threat to justify tough security measures in the resource-rich region.
Rights groups say that harsh police treatment of Uighurs and government campaigns against religious practices, such as the wearing of veils, has led to violence.
Separately, the Chinese foreign ministry said it had "lodged solemn representations" with Washington over the State Department's condemnation of the Thai deportations.
"The US statement has ignored facts and is full of political bias, and it serves as a connivance in illegal immigration and smuggling and a violation of relevant international treaties and laws," ministry spokeswoman Hua Chunying said in a statement quoted by Xinhua.