Amnesty International has called on the Royal Bank of Scotland (RBS) to closely monitor its investment in the Bank of China.
The human rights group said RBS should be making sure working conditions and pollution in firms funded by the Bank of China have improved.
The RBS said it was working with its partners in China to improve environmental and working conditions.
RBS bought a 5% stake in the Bank of China two years ago for $1.6bn.
The Edinburgh-based bank said "engagement" with China was the right way forward.
A spokesman said: "RBS is committed to respecting and upholding human rights in all areas of its operations and within its sphere of influence, as expressed in the Universal Declaration on Human Rights and the United Nations Global Compact.
"On the more general question relating to compliance with human rights and environmental standards in China, these are matters for the appropriate Chinese authorities to enforce."
RBS said the Bank of China was a highly respected international financial institution authorised to carry out business worldwide, including in the UK and US.
"Bank of China sets out its policies in its published accounts and we are happy with these policies and the way in which they are applied," the spokesman added.
However, Amnesty International said it should be watching how the money has been used in China.
John Watson, director of Amnesty in Scotland, said RBS should be monitoring its investments to check it has not been encouraging slave labour or environmental pollution.
Amnesty International has brought out two reports in the run-up to next year's Olympic Games in China which highlight the poor working conditions of migrant workers and abuses of human rights.