South Korean chipmaker SK Hynix Inc received a collaboration proposal from China's Tsinghua Unigroup Ltd but turned it down, an SK Hynix spokeswoman said on Friday, without giving further details.

She also declined to comment on media reports that the recent cooperation proposal included an offer by the Chinese technology conglomerate to purchase up to 20 percent in SK Hynix.

A Tsinghua spokesman said the company was not aware of the reported proposal.

SK Hynix shares rose a combined 8.4 percent on Wednesday and Thursday but were down 0.6 percent as of 0214 GMT on Friday, lagging the broader market's 0.1 percent gain.

Tsinghua earlier this year made an informal $23 billion takeover offer for Micron Technology Inc that was rejected out-of-hand by the Idaho-based company's leadership, although the Chinese side has not given up on a deal, sources have said.