Both China and the United States should make compromises in trade talks, Chinese Vice Commerce Minister Wang Shouwen said, ahead of meeting between the Chinese and U.S. presidents at this week's G20 summit in Japan.

Speaking at a news briefing on the G20 summit, Wang, who is also part of the trade negotiating team with the United States, said talks between the two countries' trade teams were underway, though he gave no details.

China's principles are clear, he said - mutual respect, equality and mutual benefit and meeting each other halfway.

"Mutual respect means each side must respect the other's sovereignty," Wang said.

"Equality and mutual benefit means the consultations have to happen on an equal basis, the agreement to be reached has to be beneficial for both sides," he said.

Wang declined to answer a question about what specific compromises Xi may offer to win a trade deal with Trump.