Less than 30 percent of the members of a US business lobby in China say investment conditions are improving in the world's second-largest economy, a survey showed Thursday.

Chinese authorities and state-run media have repeatedly targeted foreign firms in recent months, in sectors ranging from pharmaceuticals and baby formula to smartphones and coffee.

The survey by the American Chamber of Commerce in China showed that only 28 percent of its members who responded believe the investment environment in the country is improving, well down from 43 percent last year.

Conditions were worsening according to 19 percent, while 53 percent said they were unchanged.

The group, which lobbies on behalf of more than 1,000 US companies doing business in China, attributed the declining optimism in part to new rules that were adopted in December 2011.

They imposed "troubling new limitations" in some areas, the report said, citing prohibitions against foreign investment in the postal, transport and warehousing industries and additional hurdles related to agriculture and chemical production.

The lobbying group also lamented what it called an "opaque" investment and licensing approval process that includes "vaguely worded or unpublished rules" putting foreign companies at a disadvantage to their domestic competitors.

Foreign direct investment in China reached an all-time high of $116 billion in 2011, but dipped to $111.72 billion in 2012 amid a domestic growth slowdown and uncertainty in the West.