China has taken exception to Prime Minister Manmohan Singh's assertion that Arunachal Pradesh belongs to India and lodged a protest over it.
China has conveyed to India that it was not proper to make such comments at a time when the two countries were engaged in talks over the boundary question, sources said.
They did not specify when and where the informal protest was lodged.
Singh, during his visit to Itanagar last week, had said that Arunachal was "our land of rising sun", in a clear message that the state belongs to India.
China has been laying claim over large parts of the state and the two countries are holding talks to resolve the issue.
The Special Representatives of the two countries are working out a solution as per the Political Parameters and Guiding Principles.