* Sanan says has had preliminary contact with Osram
* Sanan says only had one face-to-face meeting with Osram
* Osram, Siemens decline comment
* Osram shares down 0.4 percent after early rise (Adds German economy ministry comment, updates shares)
SHANGHAI/BERLIN, Oct 10 (Reuters) - Chinese chipmaker Sanan Optoelectronics confirmed on Monday it had been in "preliminary contact" with Osram after reports that it was interested in buying the lighting group lifted the German firm's shares.
Osram shares had risen 2.8 percent in early trading, but fell after Sanan issued a statement saying it had only had one face-to-face meeting with the German company regarding a potential acquisition or cooperation deal. The stock was trading 0.4 percent lower at 1133 GMT.
"To date, we have not had any negotiations regarding transaction details such as the scope or the price. Neither have we signed any binding documents," Sanan said in a statement posted on the Shanghai stock exchange.
Osram is switching focus from light bulbs to lighting technology, selling its lamps unit and investing a billion euros ($1.12 billion) in a new factory in Malaysia to make chips for LED lights, making it a potential target for chipmakers such as Sanan.
If Sanan were to pursue a bid for Osram, which has a market capitalisation of 6 billion euros ($6.7 billion), it would be the biggest German company yet to be bought by a buyer from China, which is striving to become a leading industrial nation in technology within a few years.
A potential Osram suitor could buy Siemens' 17.5 percent holding in Osram as a precursor to making a takeover bid for the whole company. Siemens was not in agreement with Osram's strategy switch to invest heavily in LED chips.
Both Osram and Siemens declined to comment.
In the 4.5 billion-euro takeover of German industrial robot maker Kuka by Chinese household appliance maker Midea earlier this year, Berlin initially sought a deal to limit Midea's stake to 49 percent.
It had wanted to curb the Chinese company's influence on what it viewed as a national champion in a key industry, but eventually allowed the takeover to go through after major German shareholders in Kuka sold their stakes to Midea.
The German economy ministry said it had taken note of media reports of a Chinese takeover bid for Osram, but said it was a company issue on which it could not comment.
A ministry spokesman added that Germany was an open economy that welcomed investment by foreign companies but said the government wanted to ensure that competition with other countries was on a level playing field. ($1 = 0.8928 euros) (Reporting by Shanghai Newsroom, Paul Carrel in Berlin and Georgina Prodhan in Frankfurt; Writing by Georgina Prodhan; Editing by Ludwig Burger and Alexander Smith)