China urged other governments Thursday to “constructively help” Myanmar and Bangladesh resolve the fate of Rohingya Muslims “instead of complicating the issue” after Myanmar blocked a visit by U.N. human rights official.

Events in Rakhine state, where more than 630,000 Rohingya fled a military crackdown, are an internal affair for Myanmar that “contains complicated historical, national and religious factors,” said a foreign ministry spokeswoman, Hua Chunying.

“We think the international community should constructively help Myanmar and Bangladesh to solve the issue instead of complicating the issue,” said Hua at a regular briefing.

The U.N. official, Yanghee Lee, said Wednesday that Myanmar’s government barred her from the country. She said officials told her that was in response to her criticism of official restrictions on her movement when she visited in July.

Myanmar and Bangladesh agreed last month that some Rohingya who fled to Bangladesh could start returning on about Jan. 21. A Bangladeshi official said Tuesday that might be delayed.

Human rights groups warn the Rohingya may face more violence if they are sent back.

The government of Buddhist-majority Myanmar has refused to accept Rohingya Muslims as a minority group, though they have lived in the country for generations. Rohingya were stripped of their citizenship in 1982.