China on Friday said it hoped the United States would "fairly" handle a lawsuit filed by a Chinese-led company against President Barack Obama over a blocked wind farm project.

Ralls Corporation, a company registered in the US and controlled by directors of an arm of Chinese engineering giant Sany, sued Obama in a US court this month for signing a September 28 order to block the project in Oregon.

It has also sued the Committee on Foreign Investment in the United States (CFIUS) for barring the multi-million dollar investment over what Obama described as national security concerns.

Chinese commerce ministry spokesman Shen Danyang said China was "highly concerned" about the US rejection of the Butter Creek project.

"This is not the first time that the US government (has rejected) investment by affiliated companies of Chinese enterprises under the pretext of national security," he told reporters at a briefing.

"China will closely follow the progress of the matter... We hope US justice authorities will handle the lawsuit launched by Ralls in a just, fair and open way," he said.

Worries over Chinese companies buying into US industries considered strategic have scuttled several past deals, as in 2005 when the state-owned China National offshore Oil Corp (CNOOC) tried to take over US oil major Unocal.

This month, telecommunications equipment makers Huawei and ZTE were put on the defensive when a US Congressional committee called them potential national security threats that should be barred from US contracts and acquisitions.

Huawei and ZTE -- neither of which are state-owned -- have vehemently denied they pose any such security risk.

Privately-owned Sany also argued that it "had no motives to impede US national security" and called the blocking of the wind farm project "discriminative".

"We are confused whether (the rejection) is a political show, (bad) bureaucracy, discrimination, or viewing investment from China with a jaundiced eye," Wu Jialiang, chief executive office of Ralls, said on Thursday.

Shen said mounting US scrutiny has dampened the enthusiasm of Chinese investors.

Investment by Chinese firms in the US increased just 14.3 percent in the first nine months of the year from the same period in 2011, far lower than the 40 to 50 percent growth seen in many other countries, he said.