More than half Chinese consumers have avoided buying anything made in the United States in support of their country in an escalating trade war, a survey suggests, posing a "significant" risk to U.S. companies.

The poll conducted by London-based advisory firm Brunswick, which surveyed 1,000 Chinese consumers, said 56 percent of respondents had said they had avoided U.S. products, while 68 percent said their opinion of American firms had become more negative.

"This poses a significant bottom line risk to U.S. companies as three in four Chinese consumers say they often buy products from American businesses," Brunswick said on Wednesday.

The world's two largest economies have been caught up in a bruising trade war that has seen both sides slap tit-for-tat tariffs on each other's exports, hurting businesses and stoking concerns among firms that they could be caught up in the crossfire.

U.S. President Donald Trump and his Chinese counterpart, Xi Jinping, are set to meet for the first time in seven months at this weekend's G20 summit in Japan, but prospects for progress in the trade talks look slim.

Brunswick also surveyed 1,000 U.S. consumers for their opinions on China. It said that American opinions of Chinese companies were worsening and that 60 percent of respondents had noticed price increases on household goods since tariffs were put in place.