Tokyo has issued an entry visa to Rebiya Kadeer in readiness for next week's World Uyghur Congress, a Japan-based Uighur organisation said Friday, provoking the ire of Beijing.
"The visa was issued early Friday," said a member of the Japan Uyghur Association.
Kadeer, the exiled head of the movement, is set to arrive in Japan on Sunday for a five-day meeting of the body that China considers a "splittist" organisation.
Chinese foreign ministry spokesman Hong Lei condemned the Japanese move.
"We express our strong opposition to the relevant actions of the Japanese side," he said.
"The World Uyghur Congress is closely connected to terrorist organisations and is a downright anti-China splittist organisation," he told reporters in Beijing.
Kadeer, who lives in the US, last visited Japan in 2009.
Her visit from this weekend coincides with a summit in Beijing that will see Japanese Prime Minister Yoshihiko Noda meet his Chinese opposite number Wen Jiabao and South Korean President Lee Myung-Bak.
The World Uyghur Congress, which starts Monday, will see "hundreds of ethnic Uighurs from around 20 countries... gather in Tokyo to call for the right of self-determination," Ilham Mahmut, president of Japan Uyghur Association told AFP earlier.
This year's conference will be the fourth after previous editions were held in Munich, Germany and in Washington.
Many Uighurs complain that they are the victims of state-sanctioned persecution and marginalisation in their homeland, aided by the migration of millions of Han Chinese into the territory.
The resulting ethnic tensions have led to sporadic flashes of violence in the Xinjiang region, which is home to nine million Uighurs.