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 UN official, Yanghee Lee, said yesterday that Myanmar's government barred her from the country.
Myanmar and Bangladesh agreed last month that some Rohingya who fled to Bangladesh could start returning on about January 21. A Bangladeshi official said on 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.