An American reporter for Buzzfeed News has become the latest foreign journalist to be forced from China, which has a history of retaliating against news organizations and individual journalists for critical coverage.

Megha Rajagopalan, who was Buzzfeed News’s China bureau chief, said it was not clear why China’s Foreign Ministry declined to issue her a new journalist visa. “They say this is a process thing, we are not totally clear why,” she wrote Wednesday on Twitter.

Ms. Rajagopalan has written extensively about surveillance and mass incarceration of ethnic Uighurs and other Muslim minorities in the Xinjiang region of northwest China, subjects the Chinese authorities have tried to block journalists from covering. This month United Nations human rights experts confronted Chinese officials over estimates that one million or more Uighurs and other minorities were being held in re-education camps. Chinese officials denied the existence of the camps, saying instead that minor criminals were being assisted with rehabilitation.

The Foreign Correspondents’ Club of China said Ms. Rajagopalan’s visa denial was “extremely regrettable and unacceptable for a government that repeatedly insists it welcomes foreign media to cover the country.” Ms. Rajagopalan was the first reporter for Buzzfeed permitted to work on a regular basis in China by the Foreign Ministry. The ministry and security agencies have traditionally not allowed online-only news publications to have reporters officially live in China.

But in recent years, several online-only news organizations have asked China to give residency status to reporters they wanted to post in China. The authorities have responded by giving them temporary visas that are more easily revoked.

The Chinese government had told Buzzfeed it would allow Ms. Rajagopalan to stay in China on a visa that was valid for six months, and the visa could be renewed with the approval of officials. Ms. Rajagopalan’s visa was renewed once, but officials decided this spring not to renew it another time.