U.S. Ambassador to China Nicholas Burns said on Tuesday Washington was very concerned about China's recent "punitive" action toward some U.S. companies, and that foreign firms are delaying investments in the country due to uncertainty about the openness of its economy. Businesses groups have warned about the rise in China's use of exit bans, heightened scrutiny toward due diligence firms, and the vague wording of China's new counterespionage law, which bans the transfer of any information related to national security and broadens the definition of spying. Burns, speaking by video link with the Stimson Center think tank in Washington, said…