US Vice-President Joe Biden called on the US and China to build greater trust, but also urged Beijing to stop "outright theft" through hacking as he opened two days of annual talks between leaders of the world's two largest economies.
The annual strategic and economic dialogue is the first real chance for the new cast of diplomats and economic chiefs on both sides to discuss a wide range of issues, including trade frictions, as well as the building of a "new model" of relationships between major powers, as advocated by President Xi Jinping and his US counterpart, Barack Obama.
"Our relationship is and will continue to be a mix of competition and co-operation," Biden said in his opening remarks.
The start of the high-level dialogue followed two days of talks among officials on both sides about cybersecurity, which has been complicated by former National Security Agency contract worker Edward Snowden's revelations of electronic surveillance by the US, which also targeted Chinese networks.
There was no information from either side on whether Snowden's revelations were discussed, but Biden said Chinese theft of US intellectual property must stop.
"We both will benefit from an open, secure, reliable internet. Outright theft that we are experiencing must be viewed as out of bounds and needs to stop," he said.
Vice-Premier Wang Yang said the main aim of the dialogue was to turn the consensus reached by the presidents of the two nations into pragmatic results and to "inject concrete substance to the building of a new type of major country relationship between the two nations".
Also addressing the opening ceremony, State Councillor Yang Jiechi said China would discuss cybersecurity co-operation with the US, but added that both nations should look for ways to effectively manage their differences to set the path for the "new type of relationship".
Building such a relationship required an "innovative mindset and positive actions", he said.
US Secretary of State John Kerry said the high-level dialogue was a platform for the two sides to find ways to co-operate effectively. He said both nations recognised the complexity of their ties, and the urgency for them to find common ground for honest, wide-ranging conversation.
Kerry would return to Boston to visit his wife, who is recovering in hospital from a seizure-like episode she suffered over the weekend, Associated Press reported. US Deputy Secretary of State William Burns would take Kerry's place as co-host of the meeting with US Treasury Secretary Jack Lew, its report said.