US Secretary of State John Kerry and a top Chinese official had "candid exchanges" over several contentious issues dogging relations between Washington and Beijing, an American diplomat said on Saturday.
The pro-democracy protests in Hong Kong, human rights, cyberspying and disputes in the South China Sea -- all areas where the two nations have clashed -- were on the weighty agenda in talks between Kerry and visiting Chinese State Councillor Yang Jiechi.
Yang's trip to Kerry's hometown of Boston and the two days of talks on Friday and Saturday were also aimed at paving the ground for US President Barack Obama's trip to China next month.
A senior state department official hailed the talks -- which took place in what was described as an unusually informal atmosphere -- as "unprecedented and substantive."
The pair covered bilateral and global issues, such as Ebola, North Korea and Iran's nuclear program, where the United States and China hold broadly common views.
But they did not shy away from "a set of candid exchanges on areas of disagreement, problem areas, aimed at narrowing differences and finding ways to manage them effectively," the official said.
"And that includes human rights, and secretary Kerry, as he always does with the Chinese, raised both the basic universal principles at stake and very specific cases -- the situation in Hong Kong, which is very much in the news and on people's minds."
Kerry and Yang made brief statements to reporters before they sat down on Saturday.
Washington's top diplomat was eager to highlight "many issues that China and the United States are cooperating on, even as we have some differences that we try to manage effectively."
Yang said that the often fraught relationship between Beijing and Washington should be based on "mutual respect."
Obama travels to Beijing in November for the Asia-Pacific Economic Cooperation (APEC) summit and is expected to hold talks with President Xi Jinping on the sidelines.